de-dma uaudio

[Julian Elischer]

Kazuhito HONDA wrote:
> Hello,
> 
> Your idea is a fundamental and good one.
> I had tried your patch, and I had succeeded in using
> SB Digital Music and SB Live! 24-bit External. 
> But I guess that it isn't necessary to do pcm_getbuffersize() twice.
> 
> Sincerely,
> Kazuhito HONDA

I just MFC'd the uaudio drivers to RELENG_5 so they are pretty much identical
with -current now. pitty I forgot about it and missed 5.4..

The same de-dma patches should now be applicable to both.