net: 3c509: constify eisa_device_id

eisa_device_id are not supposed to change at runtime. All functions
working with eisa_device_id provided by <linux/eisa.h> work with
const eisa_device_id. So mark the non-const structs as const.
Signed-off-by: NArvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/3com/3c509.c

@@ -474,7 +474,7 @@ static int pnp_registered;
 #endif /* CONFIG_PNP */
 
 #ifdef CONFIG_EISA
-static struct eisa_device_id el3_eisa_ids[] = {
+static const struct eisa_device_id el3_eisa_ids[] = {
 		{ "TCM5090" },
 		{ "TCM5091" },
 		{ "TCM5092" },