rockchip: px30-firefly add standalone dts

Firefly Core-PX30-JD4 use UART2M1 while PX30 evb using UART2M0, the U-Boot
proper will use the dts setting to do the IOMUX init, and a separate dts
is needed for px30-firefly.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
4 files changed