[POWERPC] clk.h interface for platforms

This provides an implementation of the <linux/clk.h> interface for
arch/powerpc using a set of function pointers in clk_functions.
Platforms that want to support this interface should fill
clk_functions and select CONFIG_PPC_CLOCK in Kconfig.

Signed-off-by: Domen Puncer <domen.puncer@telargo.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 66a3295..26126d2 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -663,3 +663,7 @@
 	default y
 
 source "crypto/Kconfig"
+
+config PPC_CLOCK
+	bool
+	default n