[SCSI] gdth: PCI probe cleanups, prep for PCI hotplug API conversion

- Reduce uses of gdth_pci_str::pdev, preferring a local variable
  (or function arg) 'pdev' instead.

- Reduce uses of gdth_pcistr array, preferring local variable
  (or function arg) 'pcistr' instead.

- Eliminate lone use of gdth_pci_str::irq, using equivalent
  pdev->irq instead

- Eliminate assign-only gdth_pci_str::io_mm

Note:  If the indentation seems weird, that's because a line was
converted from spaces to tabs, when it was modified.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>