[build] Fix uses of literal 0 as a NULL pointer

Detected using sparse.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/3c515.c

 		outb(PKT_BUF_SZ >> 8, nic->ioaddr + TxFreeThreshold);	/* Room for a packet. */
 		/* Clear the Tx ring. */
 		for (i = 0; i < TX_RING_SIZE; i++)
-			vp->tx_skbuff[i] = 0;
+			vp->tx_skbuff[i] = NULL;
 		outl(0, nic->ioaddr + DownListPtr);
 	}
 	/* Set receiver mode: presumably accept b-case and phys addr only. */

src/drivers/net/3c595.c

 
     i = vx_connector;       /* default in EEPROM */
     reason = "default";
-    warning = 0;
+    warning = NULL;
 
     if ((vx_connectors & conn_tab[vx_connector].bit) == 0) {
         warning = "strange connector type in EEPROM.";
         i = CONNECTOR_UTP;
     }
 
-        if (warning != 0) {
+        if (warning) {
             printf("warning: %s\n", warning);
         }
         printf("selected %s. (%s)\n", conn_tab[i].name, reason);

src/drivers/net/bnx2.c

 	struct bnx2 *bp = &bnx2;
 	int i, rc;
 
-	if (pdev == 0)
-		return 0;
-
 	memset(bp, 0, sizeof(*bp));
 
 	rc = bnx2_init_board(pdev, nic);

src/drivers/net/etherfabric.c

 	}
 	else {
 		/* write to the INT_ACK register */
-		falcon_writel ( efab, 0, FCN_INT_ACK_KER_REG_A1 );
+		EFAB_ZERO_DWORD ( reg );
+		falcon_writel ( efab, &reg, FCN_INT_ACK_KER_REG_A1 );
 		mb();
 		falcon_readl ( efab, &reg,
 			       WORK_AROUND_BROKEN_PCI_READS_REG_KER_A1 );

src/drivers/net/ns8390.c

 #endif
 			0 };
 		/* if no addresses supplied, fall back on defaults */
-		if (probe_addrs == 0 || probe_addrs[0] == 0)
+		if (probe_addrs == NULL || probe_addrs[0] == 0)
 			probe_addrs = base;
 		eth_bmem = 0;		/* No shared memory */
 		for (idx = 0; (eth_nic_base = probe_addrs[idx]) != 0; ++idx) {

src/drivers/net/prism2.c

 } hfa384x_t;
 
 /* The global instance of the hardware (i.e. where we store iobase and membase, in the absence of anywhere better to put them */
-static hfa384x_t hw_global = {
-  0, 0, 0, 0, 0, 0, 0, {0,0,0,0,0,0}
-};
+static hfa384x_t hw_global;
 
 /*
  * 802.11 headers in addition to those in hfa384x_tx_frame_t (LLC and SNAP)

src/drivers/net/sis900.c

 //  {"NS 83851 PHY",0x2000, 0x5C20, MIX },
     {"RTL 8201 10/100Mbps Phyceiver"   , 0x0000, 0x8200,rtl8201_read_mode},
     {"VIA 6103 10/100Mbps Phyceiver", 0x0101, 0x8f20,vt6103_read_mode},
-    {0,0,0,0}
+    {NULL,0,0,NULL}
 };
 
 static struct mii_phy {

src/drivers/net/tlan.c

 
 static const char *media[] = {
 	"10BaseT-HD ", "10BaseT-FD ", "100baseTx-HD ",
-	"100baseTx-FD", "100baseT4", 0
+	"100baseTx-FD", "100baseT4", NULL
 };
 
 /* This much match tlan_pci_tbl[]!  */
 	{"Compaq NetFlex-3/E", 0,	/* EISA card */
 	 {0, 0, 0, 0, 0, 0},
 	 TLAN_ADAPTER_ACTIVITY_LED, 0x83},
-	{0, 0,
+	{NULL, 0,
 	 {0, 0, 0, 0, 0, 0},
 	 0, 0},
 };

src/drivers/net/tulip.c

       TULIP_IOTYPE, TULIP_SIZE, COMET },
     { "SG Thomson STE10/100A", { 0x2774104a, 0xffffffff, 0, 0, 0, 0 },
       TULIP_IOTYPE, 256, COMET },	/*Ramesh Chander*/
-    { 0, { 0, 0, 0, 0, 0, 0 }, 0, 0, 0 },
+    { NULL, { 0, 0, 0, 0, 0, 0 }, 0, 0, 0 },
 };
 
 enum tbl_flag {
     { "Xircom tulip work-alike", HAS_MII | HAS_MEDIA_TABLE | ALWAYS_CHECK_MII 
       | HAS_PWRDWN | HAS_NWAY },
     { "SGThomson STE10/100A", HAS_MII | MC_HASH_ONLY },	/*Ramesh Chander*/   
-    { 0, 0 },
+    { NULL, 0 },
 };
 
 /* A full-duplex map for media types. */
                                     0x1B03, 0x006D, /* 100baseTx, CSR12 0x1B */
                                     0x1B05, 0x006D, /* 100baseTx-FD CSR12 0x1B */
     }},
-    {0, 0, 0, 0, {}}};
+    {NULL, 0, 0, 0, {}}};
 
 static const char * block_name[] = {"21140 non-MII", "21140 MII PHY",
                                     "21142 Serial PHY", "21142 MII PHY", "21143 SYM PHY", "21143 reset method"};
 
     whereami("parse_eeprom\n");
 
-    tp->mtable = 0;
+    tp->mtable = NULL;
     /* Detect an old-style (SA only) EEPROM layout:
        memcmp(ee_data, ee_data+16, 8). */
     for (i = 0; i < 8; i ++)

src/drivers/net/via-velocity.c

 	u32 TxPhyAddr, RxPhyAddr;
 	u32 TxBufPhyAddr, RxBufPhyAddr;
 	vptr->TxDescArrays = tx_ring;
-	if (vptr->TxDescArrays == 0)
+	if (vptr->TxDescArrays == NULL)
 		printf("Allot Error");
 
 	/* Tx Descriptor needs 64 bytes alignment; */

src/hci/linux_args.c

 
 /** Supported command-line options */
 static struct option options[] = {
-	{"net", 1, 0, 'n'},
-	{"settings", 1, 0, 's'},
-	{0, 0, 0, 0}
+	{"net", 1, NULL, 'n'},
+	{"settings", 1, NULL, 's'},
+	{NULL, 0, NULL, 0}
 };
 
 /**

src/hci/mucurses/kb.c

 	int c;
 
 	if ( n == 0 ) {
-		str = '\0';
+		*str = '\0';
 		return OK;
 	}
 

src/net/udp/dns.c

 	char *fqdn;
 
 	/* Leave unchanged if already fully-qualified or no local domain */
-	if ( ( ! localdomain ) || ( strchr ( string, '.' ) != 0 ) )
+	if ( ( ! localdomain ) || ( strchr ( string, '.' ) != NULL ) )
 		return strdup ( string );
 
 	/* Append local domain to name */