firenze-pci: Fix infinite loop in firenze_pci_add_loc_code()

If ibm,slot-location-code isn't in a PCI device's parent node the loop
to search for it will never terminate since p = np->parent is always
going to return the same result.

Fixes: ab1b05d ("PCI: create optional loc-code platform callback")
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>

platforms/ibm-fsp/firenze-pci.c

@@ -987,7 +987,7 @@ void firenze_pci_add_loc_code(struct dt_node *np, struct pci_device *pd)
 	 * prefer fully-qualified slot-location-code, walk-up parent tree
 	 * to find one
 	 */
-	for (p = np->parent; p; p = np->parent) {
+	for (p = np->parent; p; p = p->parent) {
 		blcode = dt_prop_get_def(p, "ibm,slot-location-code", NULL);
 		if (blcode)
 			break;