powerpc/mpc85xx: refactor the PM operations

Freescale CoreNet-based and Non-CoreNet-based platforms require
different PM operations. This patch extracted existing PM operations
on Non-CoreNet-based platforms to a new file which can accommodate
both platforms. In this way, PM operation codes are clearer structurally.

Signed-off-by: Chenhui Zhao <chenhui.zhao@freescale.com>
Signed-off-by: Tang Yuantian <Yuantian.Tang@feescale.com>
Signed-off-by: Scott Wood <oss@buserror.net>