ROCK 5A: Missing Support for Second HDMI port

The ROCK 5A has two HDMI ports, but is based on RK3588S, which has only one HDMI controller. The second port is driven by an on-board Displayport to HDMI adapter chip, which in turn gets its signals from the USBDP PHY. The USBDP PHY and the Designware DP controller both have upstream drivers. Thus it is time to enable the second port.