fsl/sleep: updated the deep sleep framework for QorIQ platforms

fsl/sleep: updated the deep sleep framework for QorIQ platforms

With the introducing of generic board and ARM-based cores, current
deep sleep framework doesn't work anymore.
This patch will convert the current framework to adapt this change.
Basically it does:
1. Converts all the Freescale's DDR driver to support deep sleep.
2. Added basic framework support for ARM-based and PPC-based
cores separately.

Signed-off-by: Tang Yuantian <Yuantian.Tang@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>