[SCSI] gdth: update deprecated pci_find_device

Fix compilation warning in gdth.c, which was using the deprecated
pci_find_device.

drivers/scsi/gdth.c:645: warning: 'pci_find_device' is deprecated (declared at include/linux/pci.h:495)

Changing it to use pci_get_device, instead.

Signed-off-by: Sergio Luis <sergio@larces.uece.br>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>