feat(imx8ulp): adjust the voltage when sys dvfs enabled

When system level DVFS is enabled, voltage can be changed to
optimize the power consumption.

Signed-off-by: Jacky Bai <ping.bai@nxp.com>
Reviewed-by: Ye Li <ye.li@nxp.com>
Change-Id: Idfa0e637402078f3daf6e7c4ea1abb9af7675494
2 files changed