Finalize RPi Zw suport with audio

[comick]

There is a pi zero wireless build which is untested. Due to popularity of the board it makes sense to test it before 1.0.

• test boot
• test tonio daemon starts
• AP mode works
• slim kernel - remove unnecessary bloat

[comick]

Don't have a pi zero by the way.

[nomadster]

I have one, might test it if your buildroot builds gets restored properly :)
I've tried with one of the latest build a few weeks ago but got a kernel panic.

[comick]

Without one I cannot really test it :) but there's a new build every now and then, you may try the last one.

[comick]

Latest build as of writing boots and tonio daemon start when using "HDMI" at https://github.com/comick/tonio/blob/master/board/raspberrypi/rootfs_overlay/etc/tonio.conf.sample#L9

Also AP works well and could connect. There's still fat kernel that would benefit from a diet.