ACPI / dock: constify attribute_group structure

Functions working with attribute_groups provided by <linux/sysfs.h>
work with const attribute_group. These attribute_group structures do not
change at runtime so mark them as const.

File size before:
text data bss dec hex filename
7902 3528 64 11494 2ce6 drivers/acpi/dock.o

File size after:
text data bss dec hex filename
7998 3432 64 11494 2ce6 drivers/acpi/dock.o

This change was made with the help of Coccinelle.

Signed-off-by: Amitoj Kaur Chawla <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/acpi/dock.c

···
 	NULL
 };
 
-static struct attribute_group dock_attribute_group = {
+static const struct attribute_group dock_attribute_group = {
 	.attrs = dock_attributes
 };