arm64: dts: rockchip: Add USB-C port details for rk3399 Firefly

Add the initial details for the USB-C port.

Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
Link: https://lore.kernel.org/r/20210613215237.830160-4-pbrobinson@gmail.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>