mm: cma: 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.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Weißschuh <[email protected]>
Cc: Wedson Almeida Filho <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

mm/cma_sysfs.c

@@ -64,7 +64,7 @@ static struct attribute *cma_attrs[] = {
 };
 ATTRIBUTE_GROUPS(cma);
 
-static struct kobj_type cma_ktype = {
+static const struct kobj_type cma_ktype = {
 	.release = cma_kobj_release,
 	.sysfs_ops = &kobj_sysfs_ops,
 	.default_groups = cma_groups,