drivers: cosmetic: Convert SPDX license tags to Linux Kernel style

Complete in the drivers directory the work started with
commit 83d290c56fab ("SPDX: Convert all of our single
license tags to Linux Kernel style").

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
diff --git a/drivers/clk/owl/Makefile b/drivers/clk/owl/Makefile
index 9132dcc..63ab573 100644
--- a/drivers/clk/owl/Makefile
+++ b/drivers/clk/owl/Makefile
@@ -1,3 +1,3 @@
-# SPDX-License-Identifier:	GPL-2.0+
+# SPDX-License-Identifier: GPL-2.0+
 
 obj-$(CONFIG_CLK_S900) += clk_s900.o