block: make PCI device id constant

The id_table field of the struct pci_driver is constant in <linux/pci.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: Márton Németh <nm127@freemail.hu>
Cc: Julia Lawall <julia@diku.dk>
Cc: cocci@diku.dk
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/block/DAC960.c b/drivers/block/DAC960.c
index ce1fa92..7412b5d 100644
--- a/drivers/block/DAC960.c
+++ b/drivers/block/DAC960.c
@@ -7134,7 +7134,7 @@
 	.MemoryWindowSize =	DAC960_PD_RegisterWindowSize,
 };
 
-static struct pci_device_id DAC960_id_table[] = {
+static const struct pci_device_id DAC960_id_table[] = {
 	{
 		.vendor 	= PCI_VENDOR_ID_MYLEX,
 		.device		= PCI_DEVICE_ID_MYLEX_DAC960_GEM,