[openal] configuration enhancement suggestion

[Matěj Týč]

Hello,
I have a slightly uncommon sound setup and I had a minor configuration
issue with it.

I use an external USB DAC (Fiio e10) that I use, but I still have the
on-board sound card. The DAC uses a different frequency (96000) and bit
depth (24, but I don't think that is relevant).

I have set everything up in the PulseAudio (PA) daemon config file and
it mostly worked - I had just problems with some games.
Then, I have learned that putting frequency = 96000 in /etc/alsoft.conf
might fix the issue. Although I had to create that file as it wasn't
present, it indeed fixed the problem!

So I am happy now, but at the same time I think that writing values to a
config file is unnecessary since somehow querying PA what the sampling
rate of the current sound card is should do the trick.
I think that adding this auto-configuration feature would improve the
user experience for Linux DAC owners dramatically.