rockchip: rock-pi-n8: Enable on board devices

Enable common on board devices for ROCKPi N8.

- USB 2.0 Host
- USB 2.0 OTG/Gadget
- HDMI Out

Signed-off-by: Suniel Mahesh <sunil@amarulasolutions.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>