alsa-mixer: Make speaker get available=no when headphones are plugged in
While developing the new UI we had to ask ourselves the question of whether
"speakers" should be considered available when headphones are plugged in.
In most cases, they are not available and therefore we should list them
as such.
OTOH, we don't want unplugging the headphones to be considered an act of
wanting to use the speakers (the user might prefer HDMI), and there might
be line-outs that keeps the speakers from unmuting anyway. So, at this point,
I think the most reasonable would be to make the speakers have
PA_PORT_AVAILABLE_NO when headphones are plugged in and
PA_PORT_AVAILABLE_UNKNOWN when they are not. But we might want to revisit
this decision once we have the priority lists up and running.
The same reasoning applies for "Internal Mic", which should become unavailable
when any other mic is plugged in.
Signed-off-by: David Henningsson <david.henningsson@canonical.com>