mmc: core: use kobj_to_dev()

Use kobj_to_dev() instead of open-coding it.
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Minghao Chi <chi.minghao@zte.com.cn>
Link: https://lore.kernel.org/r/20220425105339.3515368-1-chi.minghao@zte.com.cnSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/core/block.c

@@ -330,7 +330,7 @@ static struct attribute *mmc_disk_attrs[] = {
 static umode_t mmc_disk_attrs_is_visible(struct kobject *kobj,
 		struct attribute *a, int n)
 {
-	struct device *dev = container_of(kobj, struct device, kobj);
+	struct device *dev = kobj_to_dev(kobj);
 	struct mmc_blk_data *md = mmc_blk_get(dev_to_disk(dev));
 	umode_t mode = a->mode;