libpayload: xHCI: Always initialize controller->pcidev

As the controller structure is never fully cleared, this one wasn't
initialized for non-pci controllers (but checked for non-null later).

Change-Id: I852671c5f55650bdb6cd97f4ec74b1f95ee894c7
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: http://review.coreboot.org/6246
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

payloads/libpayload/drivers/usb/xhci.c

@@ -169,6 +169,7 @@ xhci_init (unsigned long physical_bar)
 	controller->create_intr_queue	= xhci_create_intr_queue;
 	controller->destroy_intr_queue	= xhci_destroy_intr_queue;
 	controller->poll_intr_queue	= xhci_poll_intr_queue;
+	controller->pcidev		= 0;
 	for (i = 0; i < 128; ++i) {
 		controller->devices[i] = NULL;
 	}