handle bogus values passed to SOUND_PCM_WRITE_CHANNELS/SNDCTL_DSP_CHANNELS ioctls better- if 0 is passed, return the current setting.  if 1 or 2 are passed, behave accordingly.  treat values >2 as 2.
handle bogus values passed to SOUND_PCM_WRITE_CHANNELS/SNDCTL_DSP_CHANNELS
ioctls better- if 0 is passed, return the current setting.  if 1 or 2 are
passed, behave accordingly.  treat values >2 as 2.

PR:		kern/29964

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase