floppy: remove queue_lock around floppy_end_request

There is nothing the queue_lock could protect inside floppy_end_request,
so remove it.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>