Revert "ubifs: xattr: Don't operate on deleted inodes"

Revert "ubifs: xattr: Don't operate on deleted inodes"

This reverts commit 34ecae9939e9e873e6359f499c553a550c01384b.
UBIFS wants to assert that xattr operations are only issued on files
with positive link count. The said patch made this operations return
-ENOENT for unlinked files such that the asserts will no longer trigger.
This was wrong since xattr operations are perfectly fine on unlinked
files.
Instead the assertions need to be fixed/removed.

Cc: <stable@vger.kernel.org>
Fixes: 34ecae9939e9 ("ubifs: xattr: Don't operate on deleted inodes")
Reported-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
Tested-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Richard Weinberger <richard@nod.at>