[NETFILTER]: ip6_tables: consolidate dst and hbh matches

The matches are identical besides one looking for NEXTHDR_HOP, the other
for NEXTHDR_DEST. Remove ip6t_dst.c and handle both in ip6t_hbh.c.

Signed-off-by: Patrick McHardy <kaber@trash,net>
Signed-off-by: David S. Miller <davem@davemloft.net>