ide: separate PCI specific init from generic init in ide_pci_setup_ports()

* Setup ->mate and ->channel in ide_pci_setup_ports() instead of
  in ide_hwif_configure().

* Make 'port' parameter for ide_hwif_configure() 'unsigned int'.

* Separate PCI specific init from generic init in ide_pci_setup_ports().

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>