sgiioc4: use ->init_dma method

* Move dma_base check from sgiioc4_ide_setup_pci_device()
  to ide_dma_sgiioc4().

* Replace ide_dma_sgiioc4() 'unsigned long dma_base' argument
  by 'const struct ide_port_info *d'.

* Move hwif->INB setup from ide_init_sgiioc4() to
  sgiioc4_ide_setup_pci_device().

* Move ide_init_sgiioc4() call from sgiioc4_ide_setup_pci_device()
  to ide_dma_sgiioc4().

* Convert the driver to use ->init_dma method.

Cc: Jeremy Higdon <jeremy@sgi.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>