[SCSI] gdth: convert to PCI hotplug API

- remove PCI device sort, which greatly simplifies PCI probe,
  permitting direct, per-HBA function calls rather than an indirect
  route to the same end result.

- remove need for pcistr[]

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