ec: Only heal data/metadata when inode has enough information

Sometimes loc_t structure in a heal request doesn't contain enough
information to do an inodelk call (basically the gfid is missing).
In these cases, self heal only recovers entry information.

This is a backport of http://review.gluster.org/8368/

Change-Id: I459990c7df728ff4baf164df046672ddcde3efa5
BUG: 1140626
Signed-off-by: Xavier Hernandez <xhernandez@datalab.es>
Reviewed-on: http://review.gluster.org/8747
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>
Reviewed-by: Dan Lambright <dlambrig@redhat.com>