ubifs: Fix RENAME_WHITEOUT support

commit c3d9fda688742c06e89aa1f0f8fd943fc11468cb upstream.

Remove faulty leftover check in do_rename(), apparently introduced in a
merge that combined whiteout support changes with commit f03b8ad8
("fs: support RENAME_NOREPLACE for local filesystems")

Fixes: f03b8ad8 ("fs: support RENAME_NOREPLACE for local filesystems")
Fixes: 9e0a1fff ("ubifs: Implement RENAME_WHITEOUT")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>