sh: use common clock framework with device tree boards

Enable common clk framework for DT-based boards and disable code that
depends on the legacy sh clk framework when common clk is enabled.
Once legacy drivers are converted over, the old code can be removed
entirely.

Signed-off-by: Rich Felker <dalias@libc.org>

arch/sh/boards/Kconfig

@@ -11,6 +11,7 @@ config SH_DEVICE_TREE
 	select OF
 	select OF_EARLY_FLATTREE
 	select CLKSRC_OF
+	select COMMON_CLK
 	select GENERIC_CALIBRATE_DELAY
 	help
 	  Select Board Described by Device Tree to build a kernel that