Originally, there was a 1:1 relationship between the PCM streams' and
the low-level voices' parameters. The addition of multi-channel playback
partially invalidated that, but didn't introduce proper layering, so
things kept working only by virtue of the multi-channel device never
having two channels (yet). The upcoming addition of 32-bit playback
would complete upending the relationships.

So this patch detaches the low-level parameters from the high-level
ones: we pass pre-calculated bit width and stereo flags to the low-level
manipulation functions instead of calculating them in-place from the
stream parameters.
Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Link: https://lore.kernel.org/r/20230517174256.3657060-7-oswald.buddenhagen@gmx.deSigned-off-by: Takashi Iwai <tiwai@suse.de>