[NETFILTER]: ip_tables: compat error way cleanup

This patch adds forgotten compat_flush_offset() call to error way of
translate_compat_table().  May lead to table corruption on the next
compat_do_replace().

Signed-off-by: Vasily Averin <vvs@openvz.org>
Acked-by: Dmitry Mishin <dim@openvz.org>
Acked-by: Kirill Korotaev <dev@openvz.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>