atm: adummy: 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
 2033      1448       0    3481     d99 drivers/atm/adummy.o

File size after:
 text      data     bss     dec     hex filename
 2129      1352       0    3481     d99 drivers/atm/adummy.o

This change was made with the help of Coccinelle.
Signed-off-by: NAmitoj Kaur Chawla <amitoj1606@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/atm/adummy.c

@@ -71,7 +71,7 @@ static struct attribute *adummy_attrs[] = {
 	NULL
 };
 
-static struct attribute_group adummy_group_attrs = {
+static const struct attribute_group adummy_group_attrs = {
 	.name = NULL, /* We want them in dev's root folder */
 	.attrs = adummy_attrs
 };