ACPI / power: constify attribute_group structures

attribute_groups are not supposed to change at runtime. All functions
working with attribute_groups provided by <linux/sysfs.h> work with const
attribute_group. So mark the non-const structs as const.

File size before:
text data bss dec hex filename
4622 304 8 4934 1346 drivers/acpi/power.o

File size After adding 'const':
text data bss dec hex filename
4846 80 8 4934 1346 drivers/acpi/power.o

Signed-off-by: Arvind Yadav <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/acpi/power.c

···
 	NULL,
 };
 
-static struct attribute_group attr_groups[] = {
+static const struct attribute_group attr_groups[] = {
 	[ACPI_STATE_D0] = {
 		.name = "power_resources_D0",
 		.attrs = attrs,
···
 	},
 };
 
-static struct attribute_group wakeup_attr_group = {
+static const struct attribute_group wakeup_attr_group = {
 	.name = "power_resources_wakeup",
 	.attrs = attrs,
 };
 
 static void acpi_power_hide_list(struct acpi_device *adev,
 				 struct list_head *resources,
-				 struct attribute_group *attr_group)
+				 const struct attribute_group *attr_group)
 {
 	struct acpi_power_resource_entry *entry;
 
···
 
 static void acpi_power_expose_list(struct acpi_device *adev,
 				   struct list_head *resources,
-				   struct attribute_group *attr_group)
+				   const struct attribute_group *attr_group)
 {
 	struct acpi_power_resource_entry *entry;
 	int ret;
···
 
 static void acpi_power_expose_hide(struct acpi_device *adev,
 				   struct list_head *resources,
-				   struct attribute_group *attr_group,
+				   const struct attribute_group *attr_group,
 				   bool expose)
 {
 	if (expose)