Official 64bit raspberry pi os differences

[jonesmz]

The official rpi os 64bit image has:

only one kernel, kernel8

and these settings turned on by default

# Automatically load overlays for detected cameras
camera_auto_detect=1

# Automatically load overlays for detected DSI displays
display_auto_detect=1

# Enable DRM VC4 V3D driver
dtoverlay=vc4-kms-v3d

So for sake of aligning with upstream's official OS, we should

1. Re-work our kernel build process to have only one kernel
2. Change the vc4 overlay to vc4-kms-v3d but enable it for all pis, not just the pi4.
3. add the other two options to our config, or inherit their default value from upstream.