ARM: imx6: let pm code map CCM block on its own

ARM: imx6: let pm code map CCM block on its own

We are about to move imx6 clock driver into drivers/clk, so let's get
imx6 pm code map CCM block on its own rather than relying on clock
driver to do the mapping.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>