Comment 0 for bug 1928750

[Impact]
On Dell's platform, the MIC-Mute can't work well.

[Fix]
Here's v8 patch, support MIC-Mute of dell e-privacy feature.
Link: https://patchwork.kernel.org/project/alsa-devel/list/?series=477845
The set of patches has been verified and works well on dell's machine.
In the upstream, Hans De Goede ask dell's developer to follow ucm2 and Dell will upstream v9.
For the schedule, can't wait v9 and sru v8 first.
In the feature, will sru the final solution.

[Test Case]
1. arecord file_name
2. press mic-mute hot-key and wait 20s.
3. check the record file and can't hear voice.

[Where problems could occur]
Because the rt715 patch doesn't follow the ucm2, dell will upstream v9.
In the future, will sru the final solution again.