This is a core board named Core-PX30-JD4 with a mainboard from Firefly,
name it as firefly-px30 for now.
This board can re-use the dts of PX30, the only difference is the UART IO,
the firefly use UART2 M1 while evb use UART2 M0.
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
