UBI: remove spurious comment

This line of comment looks completely bogus.

It was introduced in:
commit d99383b0
Author: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Date:   Wed May 18 14:47:34 2011 +0300

    UBI: change the interface of a debugging check function

Remove it.

Signed-off-by: Ezequiel Garcia <elezegarcia@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>