Draft: rpi64: Add CM4 CANOPi board support

The RPi loader tries to load a dtb for u-boot from the firmware partition. Currently, the apertis-image-recipes recipes for RPi are copying these dtb files from the kernel.

It makes more sense to copy these dtb blobs from u-boot rather than the kernel, as the bootloader is the one using them. Moreover, these dtbs are built supporting overlays, which we might use for the CANOPi auto-detection support.

Signed-off-by: Ariel D'Alessandro ariel.dalessandro@collabora.com