greybus: interface: remove defensive WARN_ON

Remove defensive WARN_ON testing for a NULL-interface when removing an
interface.

Every call site has just dereferenced the interface.
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/interface.c

@@ -132,9 +132,6 @@ void gb_interface_remove(struct gb_interface *intf)
 	struct gb_bundle *bundle;
 	struct gb_bundle *next;
 
-	if (WARN_ON(!intf))
-		return;
-
 	spin_lock_irq(&gb_interfaces_lock);
 	list_del(&intf->links);
 	spin_unlock_irq(&gb_interfaces_lock);