[MTD] ck804xrom: fix a pci_find_device

Going over the bugs and warnings I found this one left over. The other
changes have already been correctly done for this driver but the actual
switch to pci_get_device that they assume has not.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>