nfs: Unable to resolve FH

Bug (965435):  while deleting files/directory from multiple machines nfs server
logs show "Unable to resolve FH" error.

Cause: The error is shown whenever the server receives rmdir/remove call and the
file/directory is already deleted. Server always shows "Unable to resolve FH"
irrespective of what is the actual error.

Fix: The error message seems little misleading therefore changed the error
message to display the actual cause.

Change-Id: I4f9c151f737317d618278c59d9f66fe9f46350b8
BUG: 965435
Signed-off-by: Rajesh Joseph <rjoseph@redhat.com>
Reviewed-on: http://review.gluster.org/5057
Reviewed-by: Santosh Pradhan <spradhan@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>