1-wire: make USB device id constant

From: Márton Németh <[email protected]>

The id_table field of the struct usb_device_id is constant in <linux/usb.h> so it is worth to make ds_id_table also constant.

The semantic match that finds this kind of pattern is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@r@
disable decl_init,const_decl_init;
identifier I1, I2, x;
@@

	struct I1 {
	  ...
	  const struct I2 *x;
	  ...
	};

@s@
identifier r.I1, y;
identifier r.x, E;
@@

	struct I1 y = {
	  .x = E,
	};

@c@
identifier r.I2;
identifier s.E;
@@

	const struct I2 E[] = ... ;

@depends on !c@
identifier r.I2;
identifier s.E;
@@
+ const

	struct I2 E[] = ...;

// </smpl>

---

diff -u -p a/drivers/w1/masters/ds2490.c b/drivers/w1/masters/ds2490.c
@@ -170,7 +170,7 @@ struct ds_status
 
 };
 
-static struct usb_device_id ds_id_table [] = {
+static const struct usb_device_id ds_id_table[] = {
 	{ USB_DEVICE(0x04fa, 0x2490) },
 	{ },
 };