usb: gadget: move bind() callback back to struct usb_composite_driver

This partly reverts 07a18bd7 ("usb gadget: don't save bind callback in
struct usb_composite_driver") and fixes new drivers. The section missmatch
problems was solved by whitelisting structs in question via __ref.

Cc: devel@driverdev.osuosl.org
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/gadget/hid.c b/drivers/usb/gadget/hid.c
index 34e139e..8502e56 100644
--- a/drivers/usb/gadget/hid.c
+++ b/drivers/usb/gadget/hid.c
@@ -247,6 +247,7 @@
 	.dev		= &device_desc,
 	.strings	= dev_strings,
 	.max_speed	= USB_SPEED_HIGH,
+	.bind		= hid_bind,
 	.unbind		= __exit_p(hid_unbind),
 };
 
@@ -272,7 +273,7 @@
 	if (status < 0)
 		return status;
 
-	status = usb_composite_probe(&hidg_driver, hid_bind);
+	status = usb_composite_probe(&hidg_driver);
 	if (status < 0)
 		platform_driver_unregister(&hidg_plat_driver);