Revert "core: fix errno for non-existent GFID"

This reverts commit 837422858c2e4ab447879a4141361fd382645406

Change-Id: I0909f26ce088454bb14b3694b489c672286a4ae6
Reviewed-on: http://review.gluster.org/6575
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>