bus: arm-ccn: 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
   9074	   5592	    416	  15082	   3aea	drivers/bus/arm-ccn.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
   9327	   5336	    416	  15079	   3ae7	drivers/bus/arm-ccn.o

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Pawel Moll <pawel.moll@arm.com>

drivers/bus/arm-ccn.c

@@ -262,7 +262,7 @@ static struct attribute *arm_ccn_pmu_format_attrs[] = {
 	NULL
 };
 
-static struct attribute_group arm_ccn_pmu_format_attr_group = {
+static const struct attribute_group arm_ccn_pmu_format_attr_group = {
 	.name = "format",
 	.attrs = arm_ccn_pmu_format_attrs,
 };
@@ -451,7 +451,7 @@ static struct arm_ccn_pmu_event arm_ccn_pmu_events[] = {
 static struct attribute
 		*arm_ccn_pmu_events_attrs[ARRAY_SIZE(arm_ccn_pmu_events) + 1];
 
-static struct attribute_group arm_ccn_pmu_events_attr_group = {
+static const struct attribute_group arm_ccn_pmu_events_attr_group = {
 	.name = "events",
 	.is_visible = arm_ccn_pmu_events_is_visible,
 	.attrs = arm_ccn_pmu_events_attrs,
@@ -548,7 +548,7 @@ static struct attribute *arm_ccn_pmu_cmp_mask_attrs[] = {
 	NULL
 };
 
-static struct attribute_group arm_ccn_pmu_cmp_mask_attr_group = {
+static const struct attribute_group arm_ccn_pmu_cmp_mask_attr_group = {
 	.name = "cmp_mask",
 	.attrs = arm_ccn_pmu_cmp_mask_attrs,
 };
@@ -569,7 +569,7 @@ static struct attribute *arm_ccn_pmu_cpumask_attrs[] = {
 	NULL,
 };
 
-static struct attribute_group arm_ccn_pmu_cpumask_attr_group = {
+static const struct attribute_group arm_ccn_pmu_cpumask_attr_group = {
 	.attrs = arm_ccn_pmu_cpumask_attrs,
 };