Raspberry Pi 4 now has overscan support

[madmodder123]

raspberrypi/linux#3090

So this script should work now right?
When trying to adjust the overscan the junk area corners of the screen don't move/update.
Manually adjusting the fields work just fine.
(I know how this script runs, I had it running on my Pi 3 just fine).

[madmodder123]

I'm pretty decent at coding, but I couldn't figure out how it draws to the framebuffer or I would just fix it myself

[ukscone]

lines 135 and 136 create the random (and zero'd) data and lines 157,181,192,217 dump the data to the display