ARM: imx5: use dynamic mapping for Cortex and GPC block

The imx5 pm code uses static mapping to access Cortex and GPC registers.
The patch create struct imx5_pm_data to encode physical address of
Cortex and GPC block, and create dynamic mapping for them at run-time.

Signed-off-by: Shawn Guo <shawn.guo@freescale.com>