Add struct ide_dma_ops and convert core code + drivers to use it.

While at it:

* Drop "ide_" prefix from ->ide_dma_end and ->ide_dma_test_irq methods.

* Drop "ide_" "infixes" from DMA methods.

* au1xxx-ide.c:
  - use auide_dma_{test_irq,end}() directly in auide_dma_timeout()

* pdc202xx_old.c:
  - drop "old_" "infixes" from DMA methods

* siimage.c:
  - add siimage_dma_test_irq() helper
  - print SATA warning in siimage_init_one()

* Remove no longer needed ->init_hwif implementations.

v2:
* Changes based on review from Sergei:
  - s/siimage_ide_dma_test_irq/siimage_dma_test_irq/
  - s/drive->hwif/hwif/ in idefloppy_pc_intr().
  - fix patch description w.r.t. au1xxx-ide changes
  - fix au1xxx-ide build
  - fix naming for cmd64*_dma_ops
  - drop "ide_" and "old_" infixes
  - s/hpt3xxx_dma_ops/hpt37x_dma_ops/
  - s/hpt370x_dma_ops/hpt370_dma_ops/
  - use correct DMA ops for HPT302/N, HPT371/N and HPT374
  - s/it821x_smart_dma_ops/it821x_pass_through_dma_ops/

v3:
* Two bugs slipped in v2 (noticed by Sergei):
  - use correct DMA ops for HPT374 (for real this time)
  - handle HPT370/HPT370A properly

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>