Revert "alsa-mixer: Set "Front" control to 0 dB on headphone path"

This reverts commit 96369919.

The commit was originally for the issue of Headphone can't output
sound, that was because the Headphone and Lineout share the 1st alsa
mixer and DAC, but this commit introduced a new issue of the speaker
is not muted after switching to headphone.

A recent merged kernel commit (f48652bbe3ae@linux) could fix the 1st
issue, so we could revert the fix of the 1st issue from PA, then the
2nd issue is fixed automatically.

BugLink: pipewire/pipewire#747


Signed-off-by: Hui Wang <hui.wang@canonical.com>
Part-of: <pulseaudio/pulseaudio!553>