block: make virtio device id constant

Author: Márton Németh <nm127@freemail.hu>

The id_table field of the struct virtio_driver is constant in 
so it is worth to make id_table also constant.

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

// 
@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[] = ...;
// 

Signed-off-by: Márton Németh 
Cc: Julia Lawall 
Cc: cocci@diku.dk
Signed-off-by: Jens Axboe 

---
 drivers/block/virtio_blk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
 
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 51042f0ba7..c17e622 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -404,7 +404,7 @@ static void __devexit virtblk_remove(struct virtio_device *vdev)
 	kfree(vblk);
 }
 
-static struct virtio_device_id id_table[] = {
+static const struct virtio_device_id id_table[] = {
 	{ VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
 	{ 0 },
 };