Omi mics, the 2nd mic and mic gain

[beastoin]

what's included?

• activate the omi consumer's 2nd mic.
• set the mic gain level to +20 dB by default for the omi consumer.
• add support to customize the mic gain level via the app.
• allow a lower min clk to support mics in low-power mode .min_pdm_clk_freq = 512000, instead of 1M.

deploy:

• deploy the omi consumer firmware https://github.com/BasedHardware/omi/releases/tag/Omi_CV1_v3.0.11
• deploy the app https://codemagic.io/app/66c95e6ec76853c447b8bcbb/build/68dc996c01d11cbfa282d576

demo:

x49.mp4

y48.mp4