[PATCH] CDROMREADAUDIO dma support

[PATCH] CDROMREADAUDIO dma support

This small patch builds on top of the blk_rq_map_user() patch just sent,
and enables us to easily support DMA for CDROMREADAUDIO cdda extraction.
It's quite amazing how much cool stuff you can with the new block layer
:-)

Patch has intelligent fall back from multi frame dma to single frame
dma, and further to old-style pio ripping in case of hardware problems.