pktgen: do not abuse IN6_ADDR_HSIZE

pktgen accidentally used IN6_ADDR_HSIZE, instead of using the size of an
IPv6 address.

Since IN6_ADDR_HSIZE recently was increased from 16 to 256, this old
bug is hitting us.

Fixes: 3f27fb23219e ("ipv6: addrconf: add per netns perturbation in inet6_addr_hash()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/pktgen.c

@@ -2165,7 +2165,7 @@ static void pktgen_setup_inject(struct pktgen_dev *pkt_dev)
 						+ pkt_dev->pkt_overhead;
 		}
 
-		for (i = 0; i < IN6_ADDR_HSIZE; i++)
+		for (i = 0; i < sizeof(struct in6_addr); i++)
 			if (pkt_dev->cur_in6_saddr.s6_addr[i]) {
 				set = 1;
 				break;