rpi-dpidac 5.10.y

• add support for 5.10.x kernel
• add support for mode 6 devices (rgb-pi, picrt, jammapi...), enable with "dtoverlay=vc4-vga666,mode6"

rpi-dpidac 5.4.79 v1

rpi-dpidac module and dtbo compiled against kernel 5.4.79