net/s390 drivers: add missing 'const' attribute

Add missing 'const' attribute to avoid the following compile warnings:

drivers/s390/net/ctcm_main.c: In function 'ctcm_init':
drivers/s390/net/ctcm_main.c:1864: warning: assignment from incompatible pointer type
drivers/s390/net/lcs.c: In function 'lcs_init_module':
drivers/s390/net/lcs.c:2468: warning: assignment from incompatible pointer type
drivers/s390/net/claw.c: In function 'claw_init':
drivers/s390/net/claw.c:3408: warning: assignment from incompatible pointer type

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/s390/net/claw.c

@@ -310,7 +310,7 @@ static struct attribute_group claw_group_attr_group = {
 	.attrs = claw_group_attrs,
 };
 
-static struct attribute_group *claw_group_attr_groups[] = {
+static const struct attribute_group *claw_group_attr_groups[] = {
 	&claw_group_attr_group,
 	NULL,
 };

drivers/s390/net/ctcm_main.c

@@ -1806,7 +1806,7 @@ static struct attribute_group ctcm_group_attr_group = {
 	.attrs = ctcm_group_attrs,
 };
 
-static struct attribute_group *ctcm_group_attr_groups[] = {
+static const struct attribute_group *ctcm_group_attr_groups[] = {
 	&ctcm_group_attr_group,
 	NULL,
 };

drivers/s390/net/lcs.c

@@ -2440,7 +2440,7 @@ static struct attribute_group lcs_group_attr_group = {
 	.attrs = lcs_group_attrs,
 };
 
-static struct attribute_group *lcs_group_attr_groups[] = {
+static const struct attribute_group *lcs_group_attr_groups[] = {
 	&lcs_group_attr_group,
 	NULL,
 };