netfilter: ipset: Make sure we always return line number on batch

Even if we return with generic IPSET_ERR_PROTOCOL it is good idea
to return line number if we called in batch mode.

Moreover we are not always exiting with IPSET_ERR_PROTOCOL. For
example hash:ip,port,net may return IPSET_ERR_HASH_RANGE_UNSUPPORTED
or IPSET_ERR_INVALID_CIDR.

Signed-off-by: Sergey Popovich <popovich_sergei@mail.ua>
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>