xen/xenbus: Remove the unnecessary check.

.. we check whether 'xdev' is NULL - but there is no need for
it as the 'dev' check is done before. The 'dev' is embedded in
the 'xdev' so having xdev != NULL with dev being being checked
is not going to happen.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/xen/xenbus/xenbus_probe_backend.c

@@ -104,8 +104,6 @@ static int xenbus_uevent_backend(struct device *dev,
 
 	xdev = to_xenbus_device(dev);
 	bus = container_of(xdev->dev.bus, struct xen_bus_type, bus);
-	if (xdev == NULL)
-		return -ENODEV;
 
 	if (add_uevent_var(env, "MODALIAS=xen-backend:%s", xdev->devicetype))
 		return -ENOMEM;