alsa/realtek: adjust max output valume for headphone on 2 LG machines

[Hui Wang]

[Impact]
In an oem project, we found the max playback volume of the headphone
is too high on 2 LG machines, it could bring harm to listeners. As
requested by OEM customer, we need to decrease the max volume.

[Fix]
Cherry-pick a mainline kernel patch, this could fix this issue.

[Test]
Booting with the patched kernel, plug the headphone, set the playback
volue to max, run:
amixer -c1 contents | grep -n2 "Headphone Playback Volume"

The value is 77,77 instead of 87,87 like below:
numid=1,iface=MIXER,name='Headphone Playback Volume'
  ; type=INTEGER,access=rw---R--,values=2,min=0,max=87,step=0
  : values=77,77

[Where problems could occur]
This patch changes the amplifier's default value, probably
will make the audio malfunction, but this change is specific
to those 2 LG machines (by SSID), will not bring regression
to other machines. For those 2 machines, we already tested patch,
the audio worked well.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux/5.15.0-104.114 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux' to 'verification-done-jammy-linux'. If the problem still exists, change the tag 'verification-needed-jammy-linux' to 'verification-failed-jammy-linux'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Hui Wang (hui.wang)]

Installed the linux/5.15.0-104.114 kernel in -proposed, and the issue is fixed by this kernel.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux/6.5.0-33.33 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-mantic-linux' to 'verification-done-mantic-linux'. If the problem still exists, change the tag 'verification-needed-mantic-linux' to 'verification-failed-mantic-linux'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Hui Wang (hui.wang)]

Installed the linux/6.5.0-33.33 kernel in -proposed, and the issue is fixed by the kernel.