libceph: don't abort reads in ceph_osdc_abort_on_full()

Don't consider reads for aborting and use ->base_oloc instead of
->target_oloc, as done in __submit_request().

Strictly speaking, we shouldn't be aborting FULL_TRY/FULL_FORCE writes
either.  But, there is an inconsistency in FULL_TRY/FULL_FORCE handling
on the OSD side [1], so given that neither of these is used in the
kernel client, leave it for when the OSD behaviour is sorted out.

[1] http://tracker.ceph.com/issues/24339



Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>