regulator: core: Make entire header comment C++ style

Makes things look more consistent.

Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/regulator/helpers.c b/drivers/regulator/helpers.c
index b9ae45d2..4986cc5 100644
--- a/drivers/regulator/helpers.c
+++ b/drivers/regulator/helpers.c
@@ -1,10 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * helpers.c  --  Voltage/Current Regulator framework helper functions.
- *
- * Copyright 2007, 2008 Wolfson Microelectronics PLC.
- * Copyright 2008 SlimLogic Ltd.
- */
+//
+// helpers.c  --  Voltage/Current Regulator framework helper functions.
+//
+// Copyright 2007, 2008 Wolfson Microelectronics PLC.
+// Copyright 2008 SlimLogic Ltd.
 
 #include <linux/kernel.h>
 #include <linux/err.h>