mtd: rawnand: nandsim: Use octal permissions

Symbolic permissions 'S_IRUSR' are not preferred. Checkpatch.pl
advises to use octal permissions '0400'.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200525085851.17682-3-miquel.raynal@bootlin.com

drivers/mtd/nand/raw/nandsim.c

@@ -508,7 +508,7 @@ static int nandsim_debugfs_create(struct nandsim *ns)
 		return 0;
 	}
 
-	dent = debugfs_create_file("nandsim_wear_report", S_IRUSR, root, ns,
+	dent = debugfs_create_file("nandsim_wear_report", 0400, root, ns,
 				   &nandsim_fops);
 	if (IS_ERR_OR_NULL(dent)) {
 		NS_ERR("cannot create \"nandsim_wear_report\" debugfs entry\n");