clk: mvebu: add Kirkwood SoC-centric clock init

This is moving core clock and clock gating init for Kirkwood to its
own file and adds a Kconfig option. Also init functions are added and
declared so they get called on of_clk_init.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
diff --git a/drivers/clk/mvebu/Kconfig b/drivers/clk/mvebu/Kconfig
index bc5f05e..211695c 100644
--- a/drivers/clk/mvebu/Kconfig
+++ b/drivers/clk/mvebu/Kconfig
@@ -13,3 +13,7 @@
 config DOVE_CLK
 	bool
 	select MVEBU_CLK_COMMON
+
+config KIRKWOOD_CLK
+	bool
+	select MVEBU_CLK_COMMON