alsa-mixer: Remove analog-output-lfe-on-mono
Upstreamed from Debian: "Although in principle Ac '97 hardware has a
separate mono LFE pin nothing seems to use it. To make matters worse
it does confuse PulseAudio's port selection slightly which causes
audio in virtualbox not to work out of the box."
Credit: Sjoerd Simons <sjoerd@debian.org>
Credit: Martin-Éric Racine <martin-eric.racine@iki.fi>
BugLink: https://bugs.launchpad.net/bugs/1016969
BugLink: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=673847
Signed-off-by: David Henningsson <david.henningsson@canonical.com>