USB: gadget: composite: added disconnect callback

Added a disconnect() callback to composite devices which
is called by composite glue when its disconnect callback
is called by gadget.

Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
index f378075..890bc14 100644
--- a/include/linux/usb/composite.h
+++ b/include/linux/usb/composite.h
@@ -276,6 +276,8 @@
 	int			(*bind)(struct usb_composite_dev *);
 	int			(*unbind)(struct usb_composite_dev *);
 
+	void			(*disconnect)(struct usb_composite_dev *);
+
 	/* global suspend hooks */
 	void			(*suspend)(struct usb_composite_dev *);
 	void			(*resume)(struct usb_composite_dev *);