Use schedule_timeout_interruptible() instead of open-coding the set and
schedule parts.

Cc: Mike Miller <mikem@beardog.cca.cpqcorp.net>
Cc: Stephen M. Cameron <scameron@beardog.cca.cpqcorp.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>