assume software volume for headset mic
requested to merge igor.v.kovalenko/pulseaudio:pr/assume-software-volume-for-headset-mic into hsp-hfp-volume
Support for remote audio volume control is optional for HSP and HFP profiles, and there is no feedback from peer for +VGM and +VGS.
In practice remote volume control is implemented for speaker and changing volume using +VGS reply works, while doing the same with +VGM for mic does not.
Assume software volume control for peer mic until peer sends AT+VGM= command which should mean peer supports remote volume control for mic as well.
This change is based on Rodrigo Araujo's work here https://lists.freedesktop.org/archives/pulseaudio-discuss/2017-September/028820.html