netfilter: ip6t_REJECT: fix a dst leak in ipv6 REJECT

commit 499031ac8a3df6738f6186ded9da853e8ea18253 upstream.

We should release dst if dst->error is set.

Bug introduced in 2.6.14 by commit e104411b82f5c
([XFRM]: Always release dst_entry on error in xfrm_lookup)

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>