xen/pci: Make xen-pcifront be dependent on XEN_XENBUS_FRONTEND

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/pci/Kconfig

@@ -45,6 +45,7 @@ config XEN_PCIDEV_FRONTEND
         depends on PCI && X86 && XEN
         select HOTPLUG
         select PCI_XEN
+	select XEN_XENBUS_FRONTEND
         default y
         help
           The PCI device frontend driver allows the kernel to import arbitrary