uss/gluster: Send success on parent lookup of entry-point

When a lookup sent to snapview-server for entry-point directory
protocol server first tries to resolve gfid of a parent directory.

looking up the parent gfid from a latest snapshot can fail if the
volume is a restored volume. As this gfid is already looked-up by
snapview-client, we can return success for the parent gfid.

Change-Id: Ic9b20561ef79b93032f07c3a81eae54a94e1747b
BUG: 1162498
Signed-off-by: vmallika <vmallika@redhat.com>
Reviewed-on: http://review.gluster.org/9229
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Raghavendra Bhat <raghavendra@redhat.com>
Reviewed-by: Rajesh Joseph <rjoseph@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>