s390/sclp_ocf: 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: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/char/sclp_ocf.c

@@ -126,7 +126,7 @@ static struct attribute *ocf_attrs[] = {
 	NULL,
 };
 
-static struct attribute_group ocf_attr_group = {
+static const struct attribute_group ocf_attr_group = {
 	.attrs = ocf_attrs,
 };