usb: isp1760: constify usb_gadget_ops structures

Declare usb_gadget_ops structures as const as they are only stored in
the ops field of a usb_gadget structure. This field is of type const, so
usb_gadget_ops structures having this property can be declared const
too.
Done using Coccinelle:

@r1 disable optional_qualifier@
identifier i;
position p;
@@
static struct usb_gadget_ops i@p={...};

@ok1@
identifier r1.i;
position p;
struct isp1760_udc udc;
@@
udc.gadget.ops=&i@p

@bad@
position p!={r1.p,ok1.p};
identifier r1.i;
@@
i@p

@depends on !bad disable optional_qualifier@
identifier r1.i;
@@
+const
struct usb_gadget_ops i;

File size before: drivers/usb/isp1760/isp1760-udc.o
   text	   data	    bss	    dec	    hex	filename
  12434	   4136	     16	  16586	   40ca	usb/isp1760/isp1760-udc.o

File size after: drivers/usb/isp1760/isp1760-udc.o
   text	   data	    bss	    dec	    hex	filename
  12530	   4048	     16	  16594	   40d2	usb/isp1760/isp1760-udc.o
Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/isp1760/isp1760-udc.c

@@ -1250,7 +1250,7 @@ static int isp1760_udc_stop(struct usb_gadget *gadget)
 	return 0;
 }
 
-static struct usb_gadget_ops isp1760_udc_ops = {
+static const struct usb_gadget_ops isp1760_udc_ops = {
 	.get_frame = isp1760_udc_get_frame,
 	.wakeup = isp1760_udc_wakeup,
 	.set_selfpowered = isp1760_udc_set_selfpowered,