[w89c840] Avoid unused variable warning in gcc 4.6

Reported-by: Ralph Giles <giles@thaumas.net>
Tested-by: Ralph Giles <giles@thaumas.net>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/w89c840.c

 
 
     u16 sum = 0;
-    int i, j;
+    int i;
     unsigned short value;
 
     if (p->ioaddr == 0)
     adjust_pci_device(p);
 
     /* Ok. Got one. Read the eeprom. */
-    for (j = 0, i = 0; i < 0x40; i++) {
+    for (i = 0; i < 0x40; i++) {
         value = eeprom_read(ioaddr, i);
         eeprom[i] = value;
         sum += value;