firmware: turris-mox-rwtm: make kobj_type structure constant

Since commit ee6d3dd ("driver core: make kobj_type constant.")
the driver core allows the usage of const struct kobj_type.

Take advantage of this to constify the structure definition to prevent
modification at runtime.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>

Author: t-8ch

drivers/firmware/turris-mox-rwtm.c

@@ -104,7 +104,7 @@ static void mox_kobj_release(struct kobject *kobj)
 	kfree(to_rwtm(kobj)->kobj);
 }
 
-static struct kobj_type mox_kobj_ktype = {
+static const struct kobj_type mox_kobj_ktype = {
 	.release	= mox_kobj_release,
 	.sysfs_ops	= &kobj_sysfs_ops,
 };