[PATCHv2] ASoC: audio-graph-card: Add audio mixer for Motorola mdm6600

[Kuninori Morimoto]

Hi Pavel

> motmdm.c handles audio configuration on "gsmtty2"; it needs to know
> whether we are in call or not; that part is in motmdm-state.c and
> listens on "gsmtty1".
> 
> To configure Alsamixer for voice calls do for example:
>     
> Speaker Right -> Voice
> Call Noise Cancellation -> Unmute
> Call Output -> Speakerphone
> Call -> 100
> Mic2 -> 40
> Left -> Mic 2
> Voice -> 55
> Mic2 -> 40
> Left -> Mic 2
> 
> Tony wrote original version using custom interface to n_gsm, Pavel
> switched it to plain serdev and split it to two drivers to be easier
> to debug and understand. Credit is Tony's, bugs are probably Pavel's.
>     
> Signed-off-by: Pavel Machek <pavel at ucw.cz>
> Co-authored-by: Tony Lindgren <tony at atomide.com>
> ---

This is not a big deal, but the this patch is not
directly related to audio-graph-card.
Including it on Subject is confusable.

Thank you for your help !!

Best regards
---
Kuninori Morimoto