rockchip: rk3399-nanopi-4: Enable IO-domain driver in SPL

rockchip: rk3399-nanopi-4: Enable IO-domain driver in SPL

The NanoPi RK3399 boards support UHS-I (up to SDR104) SD cards, however
using any of these 1.8v modes results in a boot failure in SPL upon soft
reboot.

The issue is that the "vcc_sdio" regulator is left at 1.8v on reboot
and the corresponding GPIO defaults to 3.3v. This prevents the SD card
from being reinitialized and read successfully.

This change enables the RK8XX regulators and Rockchip IO-domain drivers
in SPL, which initializes "vcc_sdio" regulator to 3.0v and configures
the GPIO for the correct level on boot.

Signed-off-by: Justin Klaassen <justin@tidylabs.net>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>