rpi64: Copy DTB Overlays from u-boot to firmware partition

Task https://phabricator.apertis.org/T9311

Depends on pkg/u-boot!78 (merged)

The RPi loader tries to load dtbs and overlays for u-boot from the firmware partition. Currently, this recipe is only copying the dtb files from u-boot, not overlays.

The CANOPi board requires the VL805 overlay in order to properly initialize the USB controller, otherwise it will hang during boot.

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