mtd_blkdevs: use lockdep_assert_held

Use lockdep_assert_held to ensure mtd_table_mutex is held instead of
mutex_trylock games.

Signed-off-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Miquel Raynal <[e-mail]>
Link: https://lore.kernel.org/linux-mtd/[e-mail]

drivers/mtd/mtd_blkdevs.c

···
 	struct gendisk *gd;
 	int ret;
 
-	if (mutex_trylock(&mtd_table_mutex)) {
-		mutex_unlock(&mtd_table_mutex);
-		BUG();
-	}
+	lockdep_assert_held(&mtd_table_mutex);
 
 	mutex_lock(&blktrans_ref_mutex);
 	list_for_each_entry(d, &tr->devs, list) {
···
 {
 	unsigned long flags;
 
-	if (mutex_trylock(&mtd_table_mutex)) {
-		mutex_unlock(&mtd_table_mutex);
-		BUG();
-	}
+	lockdep_assert_held(&mtd_table_mutex);
 
 	if (old->disk_attributes)
 		sysfs_remove_group(&disk_to_dev(old->disk)->kobj,