soc: rockchip: Fix refcount leak in rockchip_grf_init

In the Linux kernel, the following vulnerability has been resolved: soc: rockchip: Fix refcount leak in rockchip_grf_init of_find_matching_node_and_match returns a node pointer with refcount incremented, we should use of_node_put() on it when done. Add missing of_node_put() to avoid refcount leak.