[MTD] [MAPS] Fix missing printk() parameter in physmap_of.c MTD driver

Squashes a compiler warning, and provides more useful information in
the case messed up device tree information.

Signed-off-by: David Gibson <[e-mail]>
Signed-off-by: David Woodhouse <[e-mail]>

drivers/mtd/maps/physmap_of.c

···
 	else {
  		if (strcmp(of_probe, "ROM"))
 			dev_dbg(&dev->dev, "map_probe: don't know probe type "
-			"'%s', mapping as rom\n");
+			"'%s', mapping as rom\n", of_probe);
 		info->mtd = do_map_probe("mtd_rom", &info->map);
 	}
 	if (info->mtd == NULL) {