MLK-11281-10 ARM: imx: add ccm save/restore for lpsr

When exit from LPSR mode, CCM settings will be lost, so
we need to do CCM state retention support to make sure
after resume from LPSR mode, clk tree settings are same
as before entering LPSR;

Due to hardware design requirement, CCM clk root registers
access needs their parents enabled, so we use special
sequence to restore PLLs, PFDs, ROOTs, and LPCGs.

Signed-off-by: Anson Huang <b20788@freescale.com>