sound: Simplify unit fetching in dsp_oss_audioinfo()

[christos]

Summary

"i" keeps the value of the current unit, so we do not have to call
PCMUNIT() and device_get_unit() to fetch it.

In the mixer case, I think it is more correct to do it like this, since
mixer and DSP device units have a 1-1 relationship (i.e the mixer unit
is always the same as the corresponding DSP device one) and that
way we can make this more clear.

Sponsored by: The FreeBSD Foundation
MFC after: 1 week

[markj]

sys/dev/sound/pcm/dsp.c

2199–2200

IMO it would be clearer to just make unit the loop variable.

[christos]

sys/dev/sound/pcm/dsp.c

2199–2200

"i" is also used for some inner loops here (we should use a different variable probably but it doesn't hurt in this case), so unit wouldn't make much sense without introducing another loop variable for the inner loops.

[markj]

sys/dev/sound/pcm/dsp.c

2199–2200

AFAICS the use of i in the inner loops is unrelated to the use of i in the outer loop, so why can't we use unit in the outer loop and continue to use i in the inner loops?

[christos]

sys/dev/sound/pcm/dsp.c

2199–2200

I thought you meant to just rename i to unit and use it everywhere we currently have i. My bad.

[christos]

Address Mark's comments.