switch debugfs to umode_t

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/drivers/acpi/ec_sys.c b/drivers/acpi/ec_sys.c
index 6c47ae9..b258cab 100644
--- a/drivers/acpi/ec_sys.c
+++ b/drivers/acpi/ec_sys.c
@@ -105,7 +105,7 @@
 {
 	struct dentry *dev_dir;
 	char name[64];
-	mode_t mode = 0400;
+	umode_t mode = 0400;
 
 	if (ec_device_count == 0) {
 		acpi_ec_debugfs_dir = debugfs_create_dir("ec", NULL);