greybus: interface: remove unused function prototype

Remove unused gb_interface_destroy() prototype.
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Reviewed-by: Jeffrey Carlyle <jcarlyle@google.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/interface.h

@@ -61,7 +61,6 @@ struct gb_interface *gb_interface_find(struct gb_host_device *hd,
 
 struct gb_interface *gb_interface_create(struct gb_host_device *hd,
 					 u8 interface_id);
-void gb_interface_destroy(struct gb_interface *intf);
 int gb_interface_init(struct gb_interface *intf, u8 device_id);
 void gb_interface_remove(struct gb_interface *intf);
 void gb_interfaces_remove(struct gb_host_device *hd);