[PATCH] Add quirk to enable Avid Mbox 3 support

[mbarriolinares]

> Hi all,
> 
> I believe these are the right emails to send this patch to,
> but if I've missed something please let me know.
> 
> This patch enables the Avid Mbox 3 audio interface to
> be used through ALSA.  It locks the device at a 48khz sample rate.
> Then it mutes and raises the appropriate channels/inputs to allow
> for expected functionality.
> 
> Thanks for your time.

Thanks Conner for taking the time to write and submit this!

I have an MBox 3 (USB) and I've tested the patch:

1. Have not tested S/PDIF i/o because I don't have hardware to plug it.
2. Output is in mono. It seems the monitor outputs work only in MONO. 
   (with and without the front mono button switched on or off).
3. Haven't tested if Headphones output work in stereo because I don't
   have hardware for testing.
3. Inputs work great. 

I'll get a stereo 1/4'' jack to 3.5mm for testing the headphones out.
You can contact me directly if needed.