soc: rockchip: grf: Add missing of_node_put() when returning

Fix the smatch checking:
drivers/soc/rockchip/grf.c:249 rockchip_grf_init()
warn: inconsistent refcounting 'np->kobj.kref.refcount.refs.counter':

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Fixes: 75fb63a ("soc: rockchip: grf: Support multiple grf to be handled")
Closes: https://lore.kernel.org/all/aYXvgTcUJWQL2can@stanley.mountain/
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Link: https://patch.msgid.link/1770814957-17762-1-git-send-email-shawn.lin@rock-chips.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

Author: shawn1221

drivers/soc/rockchip/grf.c

@@ -231,6 +231,7 @@ static int __init rockchip_grf_init(void)
 		grf = syscon_node_to_regmap(np);
 		if (IS_ERR(grf)) {
 			pr_err("%s: could not get grf syscon\n", __func__);
+			of_node_put(np);
 			return PTR_ERR(grf);
 		}