jffs2: remove redundant check on outpos > pos

The check for outpos > pos is always false because outpos is zero
and pos is at least zero; outpos can never be greater than pos.
The check is redundant and can be removed.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>