soc: renesas: rcar-sysc: Use the correct style for SPDX License Identifier

This patch corrects the SPDX License Identifier style in
header file related to Renesas Soc driver support.
It assigns explicit block comment to the SPDX License Identifier.

Changes made by using a script provided by Joe Perches here:
https://lkml.org/lkml/2019/2/7/46.
Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com>
Link: https://lore.kernel.org/r/20200118124856.GA3421@nishadSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

drivers/soc/renesas/rcar-sysc.h

-/* SPDX-License-Identifier: GPL-2.0
- *
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
  * Renesas R-Car System Controller
  *
  * Copyright (C) 2016 Glider bvba