clk: sprd: Use the correct style for SPDX License Identifier

This patch corrects the SPDX License Identifier style
in header files related to Clock Drivers for Spreadtrum SoCs.
For C header files Documentation/process/license-rules.rst
mandates C-like comments (opposed to C source files where
C++ style should be used)

Changes made by using a script provided by Joe Perches here:
https://lkml.org/lkml/2019/2/7/46

Suggested-by: Joe Perches <[e-mail]>
Signed-off-by: Nishad Kamdar <[e-mail]>
Signed-off-by: Stephen Boyd <[e-mail]>

drivers/clk/sprd/common.h

···
-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 //
 // Spreadtrum clock infrastructure
 //

drivers/clk/sprd/composite.h

···
-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 //
 // Spreadtrum composite clock driver
 //

drivers/clk/sprd/div.h

···
-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 //
 // Spreadtrum divider clock driver
 //

drivers/clk/sprd/gate.h

···
-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 //
 // Spreadtrum gate clock driver
 //

drivers/clk/sprd/mux.h

···
-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 //
 // Spreadtrum multiplexer clock driver
 //

drivers/clk/sprd/pll.h

···
-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 //
 // Spreadtrum pll clock driver
 //