blk_alloc_ext_minor already returns just a minor number, so no need to
mask the high bits.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210824075216.1179406-2-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>