mmc: initialized disk->minors

Fix a let hunk from the blk_mq_alloc_disk conversion.

Fixes: 281ea6a5bfdc ("mmc: switch to blk_mq_alloc_disk")
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20210621080144.3655131-1-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/mmc/core/block.c

@@ -2331,6 +2331,7 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
 	md->queue.blkdata = md;
 
 	md->disk->major	= MMC_BLOCK_MAJOR;
+	md->disk->minors = perdev_minors;
 	md->disk->first_minor = devidx * perdev_minors;
 	md->disk->fops = &mmc_bdops;
 	md->disk->private_data = md;