net: dsa: mv88e6xxx: Constify struct devlink_region_ops and struct mv88e6xxx_region

'struct devlink_region_ops' and 'struct mv88e6xxx_region' are not modified
in this driver.

Constifying these structures moves some data to a read-only section, so
increases overall security, especially when the structure holds some
function pointers.

On a x86_64, with allmodconfig, as an example:
Before:
======
text data bss dec hex filename
18076 6496 64 24636 603c drivers/net/dsa/mv88e6xxx/devlink.o

After:
=====
text data bss dec hex filename
18652 5920 64 24636 603c drivers/net/dsa/mv88e6xxx/devlink.o

Signed-off-by: Christophe JAILLET <[e-mail]>
Reviewed-by: Andrew Lunn <[e-mail]>
Link: https://patch.msgid.link/4604006216[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/dsa/mv88e6xxx/devlink.c

···
 	.id = MV88E6XXX_REGION_GLOBAL1,
 };
 
-static struct devlink_region_ops mv88e6xxx_region_global1_ops = {
+static const struct devlink_region_ops mv88e6xxx_region_global1_ops = {
 	.name = "global1",
 	.snapshot = mv88e6xxx_region_global_snapshot,
 	.destructor = kfree,
···
 	.id = MV88E6XXX_REGION_GLOBAL2,
 };
 
-static struct devlink_region_ops mv88e6xxx_region_global2_ops = {
+static const struct devlink_region_ops mv88e6xxx_region_global2_ops = {
 	.name = "global2",
 	.snapshot = mv88e6xxx_region_global_snapshot,
 	.destructor = kfree,
 	.priv = &mv88e6xxx_region_global2_priv,
 };
 
-static struct devlink_region_ops mv88e6xxx_region_atu_ops = {
+static const struct devlink_region_ops mv88e6xxx_region_atu_ops = {
 	.name = "atu",
 	.snapshot = mv88e6xxx_region_atu_snapshot,
 	.destructor = kfree,
 };
 
-static struct devlink_region_ops mv88e6xxx_region_vtu_ops = {
+static const struct devlink_region_ops mv88e6xxx_region_vtu_ops = {
 	.name = "vtu",
 	.snapshot = mv88e6xxx_region_vtu_snapshot,
 	.destructor = kfree,
 };
 
-static struct devlink_region_ops mv88e6xxx_region_stu_ops = {
+static const struct devlink_region_ops mv88e6xxx_region_stu_ops = {
 	.name = "stu",
 	.snapshot = mv88e6xxx_region_stu_snapshot,
 	.destructor = kfree,
 };
 
-static struct devlink_region_ops mv88e6xxx_region_pvt_ops = {
+static const struct devlink_region_ops mv88e6xxx_region_pvt_ops = {
 	.name = "pvt",
 	.snapshot = mv88e6xxx_region_pvt_snapshot,
 	.destructor = kfree,
···
 };
 
 struct mv88e6xxx_region {
-	struct devlink_region_ops *ops;
+	const struct devlink_region_ops *ops;
 	u64 size;
 
 	bool (*cond)(struct mv88e6xxx_chip *chip);
 };
 
-static struct mv88e6xxx_region mv88e6xxx_regions[] = {
+static const struct mv88e6xxx_region mv88e6xxx_regions[] = {
 	[MV88E6XXX_REGION_GLOBAL1] = {
 		.ops = &mv88e6xxx_region_global1_ops,
 		.size = 32 * sizeof(u16)
···
 {
 	bool (*cond)(struct mv88e6xxx_chip *chip);
 	struct mv88e6xxx_chip *chip = ds->priv;
-	struct devlink_region_ops *ops;
+	const struct devlink_region_ops *ops;
 	struct devlink_region *region;
 	u64 size;
 	int i, j;