USB serial: 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>

diff --git a/drivers/usb/serial/keyspan.h b/drivers/usb/serial/keyspan.h
index 30771e5..bf3297d 100644
--- a/drivers/usb/serial/keyspan.h
+++ b/drivers/usb/serial/keyspan.h
@@ -456,7 +456,7 @@
 	NULL,
 };
 
-static struct usb_device_id keyspan_ids_combined[] = {
+static const struct usb_device_id keyspan_ids_combined[] = {
 	{ USB_DEVICE(KEYSPAN_VENDOR_ID, keyspan_usa18x_pre_product_id) },
 	{ USB_DEVICE(KEYSPAN_VENDOR_ID, keyspan_usa19_pre_product_id) },
 	{ USB_DEVICE(KEYSPAN_VENDOR_ID, keyspan_usa19w_pre_product_id) },
@@ -497,7 +497,7 @@
 };
 
 /* usb_device_id table for the pre-firmware download keyspan devices */
-static struct usb_device_id keyspan_pre_ids[] = {
+static const struct usb_device_id keyspan_pre_ids[] = {
 	{ USB_DEVICE(KEYSPAN_VENDOR_ID, keyspan_usa18x_pre_product_id) },
 	{ USB_DEVICE(KEYSPAN_VENDOR_ID, keyspan_usa19_pre_product_id) },
 	{ USB_DEVICE(KEYSPAN_VENDOR_ID, keyspan_usa19qi_pre_product_id) },
@@ -513,7 +513,7 @@
 	{ } /* Terminating entry */
 };
 
-static struct usb_device_id keyspan_1port_ids[] = {
+static const struct usb_device_id keyspan_1port_ids[] = {
 	{ USB_DEVICE(KEYSPAN_VENDOR_ID, keyspan_usa18x_product_id) },
 	{ USB_DEVICE(KEYSPAN_VENDOR_ID, keyspan_usa19_product_id) },
 	{ USB_DEVICE(KEYSPAN_VENDOR_ID, keyspan_usa19qi_product_id) },
@@ -524,7 +524,7 @@
 	{ } /* Terminating entry */
 };
 
-static struct usb_device_id keyspan_2port_ids[] = {
+static const struct usb_device_id keyspan_2port_ids[] = {
 	{ USB_DEVICE(KEYSPAN_VENDOR_ID, keyspan_usa28_product_id) },
 	{ USB_DEVICE(KEYSPAN_VENDOR_ID, keyspan_usa28x_product_id) },
 	{ USB_DEVICE(KEYSPAN_VENDOR_ID, keyspan_usa28xa_product_id) },
@@ -532,7 +532,7 @@
 	{ } /* Terminating entry */
 };
 
-static struct usb_device_id keyspan_4port_ids[] = {
+static const struct usb_device_id keyspan_4port_ids[] = {
 	{ USB_DEVICE(KEYSPAN_VENDOR_ID, keyspan_usa49w_product_id) },
 	{ USB_DEVICE(KEYSPAN_VENDOR_ID, keyspan_usa49wlc_product_id)},
 	{ USB_DEVICE(KEYSPAN_VENDOR_ID, keyspan_usa49wg_product_id)},