ofp-util: Use OFPGMFC_OUT_OF_BUCKETS for indirect groups with !=1 buckets.

ofp-util: Use OFPGMFC_OUT_OF_BUCKETS for indirect groups with !=1 buckets.

OpenFlow 1.3 says:

    If a switch cannot add the incoming group entry due to restrictions
    (hardware or otherwise) limiting the number of group buckets, it must
    refuse to add the group entry and must send an ofp_error_msg with
    OFPET_GROUP_MOD_FAILED type and OFPGMFC_OUT_OF_BUCKETS code.

This indicates that OFPGMFC_OUT_OF_BUCKETS is appropriate for an indirect
group with the wrong number of buckets, but OVS was using a different
error.  This fixes the problem.

ONF-JIRA: EXT-546
Reported-by: Mrinmoy Das <mrdas@ixiacom.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Justin Pettit <jpettit@nicira.com>