usb: gadget: push all usb_composite_driver structs into __refdata

As it turns out, Sam's comment was better than I initially assumed. This
patch pushes as struct usb_composite_driver data structures into
__refdata section to avoid a section missmatch report from modpost
because the ->bind() can be marked __init. The only downside is that
modpost does not check between ->bind() and other member. However, it is
temporary.

Cc: Sam Ravnborg <sam@ravnborg.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>

drivers/usb/gadget/webcam.c

@@ -390,7 +390,7 @@ error:
  * Driver
  */
 
-static struct usb_composite_driver webcam_driver = {
+static __refdata struct usb_composite_driver webcam_driver = {
 	.name		= "g_webcam",
 	.dev		= &webcam_device_descriptor,
 	.strings	= webcam_device_strings,