acpi: make ACPI device id constant

The ids field of the struct acpi_driver is constant in <linux/acpi/acpi_bus.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: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/power_meter.c b/drivers/acpi/power_meter.c
index 2ef7030..ca75c36 100644
--- a/drivers/acpi/power_meter.c
+++ b/drivers/acpi/power_meter.c
@@ -64,7 +64,7 @@
 	return force_cap_on || cap_in_hardware;
 }
 
-static struct acpi_device_id power_meter_ids[] = {
+static const struct acpi_device_id power_meter_ids[] = {
 	{"ACPI000D", 0},
 	{"", 0},
 };