soc: rockchip: Fix refcount leak in rockchip_grf_init

[ Upstream commit 9b59588d ]

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.

Fixes: 4c58063d

 ("soc: rockchip: add driver handling grf setup")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Link: https://lore.kernel.org/r/20220516072013.19731-1-linmq006@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>