Push the lock_kernel down into the driver and switch to unlocked_ioctl

[akpm@linux-foundation.org: build fix]
Signed-off-by: Alan Cox <alan@redhat.com>
Acked-by: Peter Osterlund <petero2@telia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>