include: usb: composite: add USB_GADGET_DELAYED_STATUS to avoid compilation error

Added USB_GADGET_DELAYED_STATUS to avoid the following compilation error.
error: ‘USB_GADGET_DELAYED_STATUS’ undeclared (first use in this function)
while compiling dwc3/ep0.c

While this is been added only to avoid compilation error, the complete fix
should be something like the one added in linux kernel. The complete fix
will be ported once we have the composite driver in u-boot look similar to
the one in linux kernel.
commit 1b9ba000177ee47bcc5b44c7c34e48e735f5f9b1
Author: Roger Quadros <roger.quadros@nokia.com>
Date:   Mon May 9 13:08:06 2011 +0300

    usb: gadget: composite: Allow function drivers to pause control transfers

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Reviewed-by: Lukasz Majewski <l.majewski@samsung.com>

include/linux/usb/composite.h

@@ -27,6 +27,15 @@
 #include <linux/usb/gadget.h>
 #include <usb/lin_gadget_compat.h>
 
+/*
+ * USB function drivers should return USB_GADGET_DELAYED_STATUS if they
+ * wish to delay the data/status stages of the control transfer till they
+ * are ready. The control transfer will then be kept from completing till
+ * all the function drivers that requested for USB_GADGET_DELAYED_STAUS
+ * invoke usb_composite_setup_continue().
+ */
+#define	USB_GADGET_DELAYED_STATUS	0x7fff /* Impossibly large value */
+
 struct usb_configuration;
 
 /**