RaspberryPi RP1 is a multi function PCI endpoint device that
exposes several subperipherals via PCI BAR.
Add a dtb overlay that will be compiled into a binary blob
and linked in the RP1 driver.
This overlay offers just minimal support to represent the
RP1 device itself, the sub-peripherals will be added by
future patches.
Signed-off-by: Andrea della Porta <andrea.porta@xxxxxxxx>