clk: mvebu: kirkwood: maintain clock init order

Init order of CLK_OF_DECLARE'd drivers depends on compile order.
Unfortunately, clk_of_init does not allow drivers to return errors,
e.g. -EPROBE_DEFER if parent clocks have not been registered, yet.

To avoid init order woes for MVEBU clock drivers, we take care of
proper init order ourselves. This patch joins core-clk and gating-clk
init to maintain proper init order.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Tested-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>