block: use put_device in put_disk

block: use put_device in put_disk

Use put_device to put the device instead of poking into the internals
and using kobject_put.

Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>
Reviewed-by: Johannes Thumshirn <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>