The do_multirule logic was broken in batch mode because
it expected the preferred_family to be AF_INET or AF_INET6,
but it then assigned it to RTNL_FAMILY_IPMR or RTNL_FAMILY_IP6MR.
So, the next iteration of the batch processing, it failed
the check for AF_INET or AF_INET6.
Signed-off-by: Ben Greear <greearb@candelatech.com>