mtdblock: make warning messages ratelimited

When exercising various dev interfaces with stress-ng the mtdblock drivers
can be (ab)used to generate a lot of warning messages. Make these rate
limited to reduce the kernel log from being spammed with the same messages.

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

drivers/mtd/mtdblock.c

···
 	}
 
 	if (mtd_type_is_nand(mbd->mtd))
-		pr_warn("%s: MTD device '%s' is NAND, please consider using UBI block devices instead.\n",
+		pr_warn_ratelimited("%s: MTD device '%s' is NAND, please consider using UBI block devices instead.\n",
 			mbd->tr->name, mbd->mtd->name);
 
 	/* OK, it's not open. Create cache info for it */

drivers/mtd/mtdblock_ro.c

···
 	dev->readonly = 1;
 
 	if (mtd_type_is_nand(mtd))
-		pr_warn("%s: MTD device '%s' is NAND, please consider using UBI block devices instead.\n",
+		pr_warn_ratelimited("%s: MTD device '%s' is NAND, please consider using UBI block devices instead.\n",
 			tr->name, mtd->name);
 
 	if (add_mtd_blktrans_dev(dev))