No mixer with Snapper

[Justin Hibbits]

After upgrading my kernel to one with the Snapper audio driver integrated, there
is no longer a /dev/mixer, so mixer setting does not work.  I have a DSP device,
   and sound does play, it's just very quiet.  Output from sndstat is:

FreeBSD Audio Driver (newpcm: 32bit 2007061600/powerpc)
Installed devices:
pcm0: <Apple I2S Audio Controller> at i2s [MPSAFE] (1p:1v/0r:0v channels default)

Previously I was using Marco's AOA2 patch, which worked well, and had an
adjustable mixer.

- Justin