The io-domains on Rockchip SoCs will be supplied with 1.8V or 3.3V(3.0V)
depends on hardware design. The driver needs to config them through grf
register.
Change-Id: Ic896b94bfadd0b808da54992e58e2cf4a8fee950
Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>