USB: gadget.h depends on ch9.h so include ch9.h directly

The struct definitions are used.
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

include/linux/usb/gadget.h

@@ -16,6 +16,7 @@
 #define __LINUX_USB_GADGET_H
 
 #include <linux/slab.h>
+#include <linux/usb/ch9.h>
 
 struct usb_ep;