wireless: ipw2200: constify attribute_group structures.

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

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wireless/intel/ipw2x00/ipw2200.c

@@ -11500,7 +11500,7 @@ static struct attribute *ipw_sysfs_entries[] = {
 	NULL
 };
 
-static struct attribute_group ipw_attribute_group = {
+static const struct attribute_group ipw_attribute_group = {
 	.name = NULL,		/* put in device directory */
 	.attrs = ipw_sysfs_entries,
 };