[PATCH] dm: fix error number

Return -ENOTBLK if lookup_device() finds the inode, but it
is not a block device. [Cristoph Hellwig]

drivers/md/dm-table.c

@@ -312,7 +312,7 @@ static int lookup_device(const char *path, dev_t *dev)
 	}
 
 	if (!S_ISBLK(inode->i_mode)) {
-		r = -EINVAL;
+		r = -ENOTBLK;
 		goto out;
 	}