[sis190] Fix building with GCC 6

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

src/drivers/net/sis190.c

 static const u32 sis190_intr_mask =
 	RxQEmpty | RxQInt | TxQ1Int | TxQ0Int | RxHalt | TxHalt | LinkChange;
 
-/*
- * Maximum number of multicast addresses to filter (vs. Rx-all-multicast).
- * The chips use a 64 element hash table based on the Ethernet CRC.
- */
-static const int multicast_filter_limit = 32;
-
 static void __mdio_cmd(void *ioaddr, u32 ctl)
 {
 	unsigned int i;

src/drivers/net/sis190.h

 	{ NULL, { 0x00, 0x00 }, 0, 0 }
 };
 
-static const struct {
-	const char *name;
-} sis_chip_info[] = {
-	{ "SiS 190 PCI Fast Ethernet adapter" },
-	{ "SiS 191 PCI Gigabit Ethernet adapter" },
-};
-
 static void sis190_phy_task(struct sis190_private *tp);
 static void sis190_free(struct net_device *dev);
 static inline void sis190_init_rxfilter(struct net_device *dev);