drm/amdkfd: Fix memory leaks in kfd topology

Kobject created using kobject_create_and_add() can be freed using
kobject_put() when there is no referenece any more. However,
kobject memory allocated with kzalloc() has to set up a release
callback in order to free it when the counter decreases to 0.
Otherwise it causes memory leak.

Signed-off-by: Yong Zhao <yong.zhao@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>