Support Raspbian-buster-arm64

[StuartIanNaylor]

https://downloads.raspberrypi.org/raspios_arm64/images/raspios_arm64-2020-05-28/2020-05-27-raspios-buster-arm64.zip

[HinTak]

The respeaker driver code has no arch-dependent code, so it should just work on 64-bit arm. Assuming raspbian 64-bit is also on the 4.19 kernels like raspbian 32-bit, it should just work.

[HinTak]

FYI. See #240 , which is likely a 64-bit issue.

edit: fixed - it is just amixer accidentally turning recording volume of channel 3 really low, rather than selecting headphone for output, when run against newer kernel. works perfectly for me on the 6-mic device with ubuntu 64-bit now.

[StuartIanNaylor]

I have found an alternative driver so its ok.

[HinTak]

FWIW, the 2-mic device is quite different from the two 4-mics and 6-mics ones - the 2-mics device is based on wm8960, while all the other 3 are based on ac108 (single or dual ac108, in the case of dual ac108, plus a ac101).

The wm8960 code itself is just better supported - it is in fact built into later kernels - I have definitely seen it within 5.7.