Fix incorrect verdict check and returns error if device_create failed,
otherwise driver triggers kernel oops.

Signed-off-by: Joonwoo <Park&lt;joonwpark81@gmail.com>
Cc: Rodolfo Giometti <giometti@enneenne.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>