clk: meson: use SPDX license identifiers consistently

Replace every license notices in drivers/clk/meson by SPDX license
identifiers, as described in license-rules.rst

Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>

drivers/clk/meson/clk-regmap.h

@@ -1,6 +1,8 @@
-// SPDX-License-Identifier: GPL-2.0
-// Copyright (c) 2018 BayLibre, SAS.
-// Author: Jerome Brunet <jbrunet@baylibre.com>
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2018 BayLibre, SAS.
+ * Author: Jerome Brunet <jbrunet@baylibre.com>
+ */
 
 #ifndef __CLK_REGMAP_H
 #define __CLK_REGMAP_H