[tg3] Add support for tg3-5721

From: Daniel Mealha Cabrita <dancab@utfpr.edu.br>

I've added tg3-5721 support for gPXE, the patch (against gpxe-0.9.3) is
attached to this message.

This chipset is present in HP ML150 G2 servers (possibly other HP machines
as well).

src/drivers/net/tg3.c

 	     (65 << GRC_MISC_CFG_PRESCALAR_SHIFT));
 
 	/* Initialize MBUF/DESC pool. */
-	if (GET_ASIC_REV(tp->pci_chip_rev_id) != ASIC_REV_5705) {
+	if ((GET_ASIC_REV(tp->pci_chip_rev_id) != ASIC_REV_5705) &&
+		(tp->pci_chip_rev_id != CHIPREV_ID_5721)) {
 		tw32(BUFMGR_MB_POOL_ADDR, NIC_SRAM_MBUF_POOL_BASE);
 		if (GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5704)
 			tw32(BUFMGR_MB_POOL_SIZE, NIC_SRAM_MBUF_POOL_SIZE64);
 PCI_ROM(0x14e4, 0x164d, "tg3-5702FE",      "Broadcom Tigon 3 5702FE"),
 PCI_ROM(0x14e4, 0x1653, "tg3-5705",        "Broadcom Tigon 3 5705"),
 PCI_ROM(0x14e4, 0x1654, "tg3-5705_2",      "Broadcom Tigon 3 5705_2"),
+PCI_ROM(0x14e4, 0x1659, "tg3-5721",        "Broadcom Tigon 3 5721"),
 PCI_ROM(0x14e4, 0x165d, "tg3-5705M",       "Broadcom Tigon 3 5705M"),
 PCI_ROM(0x14e4, 0x165e, "tg3-5705M_2",     "Broadcom Tigon 3 5705M_2"),
 PCI_ROM(0x14e4, 0x1677, "tg3-5751",        "Broadcom Tigon 3 5751"),

src/drivers/net/tg3.h

 #define  CHIPREV_ID_5705_A1		 0x3001
 #define	 CHIPREV_ID_5705_A2              0x3002
 #define  CHIPREV_ID_5705_A3              0x3003
+#define  CHIPREV_ID_5721                 0x4101
 #define  CHIPREV_ID_5750_A0              0x4000
 #define  CHIPREV_ID_5750_A1              0x4001
 #define  CHIPREV_ID_5750_A3              0x4003