mtd: change positive error return into negative

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/mtdchar.c

@@ -373,7 +373,7 @@ static int mtd_do_writeoob(struct file *file, struct mtd_info *mtd,
 	if (!mtd->write_oob)
 		ret = -EOPNOTSUPP;
 	else
-		ret = access_ok(VERIFY_READ, ptr, length) ? 0 : EFAULT;
+		ret = access_ok(VERIFY_READ, ptr, length) ? 0 : -EFAULT;
 
 	if (ret)
 		return ret;