net: tilegx driver: avoid compiler warning

The "id" variable was being incremented in common code, but only
initialized and used in IPv4 code. We move the increment to the IPv4
code too, and then legitimately use the uninitialized_var() macro to
avoid the gcc 4.6 warning that 'id' may be used uninitialized.
Note that gcc 4.7 does not warn.

Signed-off-by: Chris Metcalf <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/tile/tilegx.c

···
 	unsigned int data_len = skb->len - sh_len;
 	unsigned char *data = skb->data;
 	unsigned int ih_off, th_off, p_len;
-	unsigned int isum_seed, tsum_seed, id, seq;
+	unsigned int isum_seed, tsum_seed, seq;
+	unsigned int uninitialized_var(id);
 	int is_ipv6;
 	long f_id = -1;    /* id of the current fragment */
 	long f_size = skb_headlen(skb) - sh_len;  /* current fragment size */
···
 		} else {
 			ih = (struct iphdr *)(buf + ih_off);
 			ih->tot_len = htons(sh_len + p_len - ih_off);
-			ih->id = htons(id);
+			ih->id = htons(id++);
 			ih->check = csum_long(isum_seed + ih->tot_len +
 					      ih->id) ^ 0xffff;
 		}
···
 			slot++;
 		}
 
-		id++;
 		seq += p_len;
 
 		/* The last segment may be less than gso_size. */