staging: hikey9xx: hi6421v600-regulator: do some cleanups

Use C99 comments at the beginning of the file and remove
uneeded includes.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/cc0017d65b49ceb7df0357cec3a2dc1c4c2a118d.1611212783.git.mchehab+huawei@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/hikey9xx/hi6421v600-regulator.c

 // SPDX-License-Identifier: GPL-2.0
-/*
- * Device driver for regulators in Hisi IC
- *
- * Copyright (c) 2013 Linaro Ltd.
- * Copyright (c) 2011 Hisilicon.
- *
- * Guodong Xu <guodong.xu@linaro.org>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- */
+//
+// Device driver for regulators in Hisi IC
+//
+// Copyright (c) 2013 Linaro Ltd.
+// Copyright (c) 2011 Hisilicon.
+//
+// Guodong Xu <guodong.xu@linaro.org>
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
 
-#include <linux/delay.h>
-#include <linux/device.h>
-#include <linux/err.h>
-#include <linux/io.h>
 #include <linux/mfd/hi6421-spmi-pmic.h>
 #include <linux/module.h>
-#include <linux/of_address.h>
-#include <linux/of_device.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/regulator/driver.h>
 #include <linux/regulator/machine.h>
 #include <linux/regulator/of_regulator.h>
-#include <linux/seq_file.h>
-#include <linux/slab.h>
 #include <linux/spmi.h>
-#include <linux/time.h>
-#include <linux/uaccess.h>
 
 #define rdev_dbg(rdev, fmt, arg...)	\
 		 pr_debug("%s: %s: " fmt, (rdev)->desc->name, __func__, ##arg)