Staging: xgifb: change obsolete pci_find_device() with pci_get_device()

Replaced obsolete pci_find_device() calls with pci_get_device() calls.
This is recommended in pci.txt filei in PCI Documentation.

Signed-off-by: Atul Sowani <sowani@gmail.com>
Acked-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>