Make config pp_usb_aud_xk_316_mc for custom board

[andry.vinogradov]

Make config pp_usb_aud_xk_316_mc for custom board

comopnets avaliable on board:
1x XU316-1024-TQ128-I24
2x PCM1865DBT
1x Si5351A-B-GT
1xPCA9540BD,118
all componets connecded as in reference board XK-AUDIO-316-MC-AB
clock is Si5351A-B-GT conneted direclu to xmos without multiplexers

[Ross]

This should be a simple job.

I'd use the internal PLL in the xcore to generate the mclk though. Probably you don't need the i2c multiplexor. I think we needed to use this on the xmos board due to address clashes.