USB image: make USB device id constant

The id_table field of the struct usb_device_id is constant in <linux/usb.h>
so it is worth to make the initialization data 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>
Signed-off-by: Németh Márton <nm127@freemail.hu>
Cc: Julia Lawall <julia@diku.dk>
Cc: cocci@diku.dk
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/image/mdc800.c

@@ -967,7 +967,7 @@ static const struct file_operations mdc800_device_ops =
 
 
 
-static struct usb_device_id mdc800_table [] = {
+static const struct usb_device_id mdc800_table[] = {
 	{ USB_DEVICE(MDC800_VENDOR_ID, MDC800_PRODUCT_ID) },
 	{ }						/* Terminating entry */
 };

drivers/usb/image/microtek.c

@@ -155,7 +155,7 @@ static int mts_usb_probe(struct usb_interface *intf,
 			 const struct usb_device_id *id);
 static void mts_usb_disconnect(struct usb_interface *intf);
 
-static struct usb_device_id mts_usb_ids [];
+static const struct usb_device_id mts_usb_ids[];
 
 static struct usb_driver mts_usb_driver = {
 	.name =		"microtekX6",
@@ -656,7 +656,7 @@ static struct scsi_host_template mts_scsi_host_template = {
 /* The entries of microtek_table must correspond, line-by-line to
    the entries of mts_supported_products[]. */
 
-static struct usb_device_id mts_usb_ids [] =
+static const struct usb_device_id mts_usb_ids[] =
 {
 	{ USB_DEVICE(0x4ce, 0x0300) },
 	{ USB_DEVICE(0x5da, 0x0094) },