Various dma relates cleanups
Changes since v1: - include important fixes from Ondrej
- dma related cleanups for wd719x v2 Christoph Hellwig
- [PATCH 1/3] wd719x: there should be no active SCBs... Christoph Hellwig
- [PATCH 2/3] wd719x: use per-command private data Christoph Hellwig
- [PATCH 3/3] wd719x: always use generic DMA API Christoph Hellwig
- Re: dma related cleanups for wd719x v2 Martin K. Petersen
