cs5530/sc1200: add PIO autotune fallback to ->ide_dma_check
* Add PIO autotune fallback to ->ide_dma_check.
Since cs5530/sc1200 allow separate PIO and DMA timings, and cs5530/sc1200
always set ->autotune this change shouldn't have any other effect than
bringing these drivers in-line with other host drivers wrt ->ide_dma_check
implementations.
* Fix ->ide_dma_check to return "-1" if DMA cannot be set.