[RPi4] Check if rootfs space allows for including rtl8812au module

[acostach]

The rootfs has become pretty packed now, however, we can check if there's still enough space left to include the
rt8812au module for the Pi4. For this we need to add the driver sources, do necessary changes to make sure it builds with the Rpi kernel, merge the PR, then execute a HUP test.

If this doesn't work, then we'll be able to include the driver only after the Host extensions become available.

[jellyfish-bot]

[acostach] This issue has attached support thread https://jel.ly.fish/298ab8e9-502e-4767-b2a4-0c5ffb8db139

[acostach]

Error response from daemon: failed to copy files: copy file range failed: no space left on device

Currently there is not enough space in the rootfs to include this module