chtrt5645: Restore stereo sound output when switching from MonoSpeaker to Headphones

chtrt5645: Restore stereo sound output when switching from MonoSpeaker to Headphones

Commit fe3b0bdc2f43 ("chtrt5645: merge all possible configurations to
HiFi.conf") missed the part of the removed HiFi-mono-speaker-analog-mic.conf
file which restores stereo mixing (instead of mixing left + right to the
left DAC mixer output) when switching from the mono speaker setup to the
headphones output.

This was causing both left and right channels to only be played on the
left ear of the headphones. This commit fixes this.

Fixes: fe3b0bdc2f43 ("chtrt5645: merge all possible configurations to HiFi.conf")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>