sgiioc4: use ide_tune_dma()

* Add DRV_NAME define and use it instead of sgiioc4_chipset.name.

* Remove no longer needed sgiioc4_chipset.

* Remove needless clearing of ->atapi_dma from ide_dma_sgiioc4().

* Fix ide_dma_sgiioc4() to return success/failure.  Check return value in
  sgiioc4_ide_setup_pci_device() and set hwif->autodma accordingly.  Also add
  missing setting of drive->autodma.

* Add sgiioc4_speedproc() (implementation of ->speedproc method).

* Fix ->mwdma_mask (MWDMA2 mask is 0x04 not 0x02) and remove incorrect
  ->swdma_mask.  Also remove needless initialization of ->ultra_mask.

* Use ide_tune_dma() in sgiioc4_ide_dma_check(), this fixes following bugs:
  - DMA capability bit not being checked on the device
  - DMA blacklist not being checked
  - MWDMA2 mode support by device not being checked

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