built from optee commit:
201e349 plat: rk312x: add ddr change frequency function
1)add ddr change frequency function
2)add wait_cpus_into_wfe support
Change-Id: Ic0e1c6606079d781e6c9b87169f76f6f41e1934e
Signed-off-by: XiaoDong Huang <derrick.huang@rock-chips.com>