cluster/dht: Return success in dht_discover if layout issues

We cannot heal in dht_discover, as it is a gfid based lookup, and not
path based. So, returning error here would lead to app's to see failure.

Also, update the layout in inode_ctx even if it has anomalies. Let
subsequent heals fix the issue.

Change-Id: I2358aadacf9a24e20a22ab0a6055c38c5eb6485c
BUG: 960348
Original-author: shishir gowda <sgowda@redhat.com>
Signed-off-by: shishir gowda <sgowda@redhat.com>
Signed-off-by: Jeff Darcy <jdarcy@redhat.com>
Reviewed-on: http://review.gluster.org/4959
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>