[IPV6] route: kill some bloat

net/ipv6/route.c:
  ip6_pkt_prohibit_out | -130
  ip6_pkt_discard      | -261
  ip6_pkt_discard_out  | -130
  ip6_pkt_prohibit     | -261
 4 functions changed, 782 bytes removed, diff: -782

net/ipv6/route.c:
  ip6_pkt_drop | +300
 1 function changed, 300 bytes added, diff: +300

net/ipv6/route.o:
 5 functions changed, 300 bytes added, 782 bytes removed, diff: -482

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>