mailbox: mtk: add missing of_node_put before return

Fix following coccicheck warning:
WARNING: Function "for_each_child_of_node"
should have of_node_put() before return.

Early exits from for_each_child_of_node should decrement the
node reference counter.

Signed-off-by: Wang Qing <[e-mail]>
Signed-off-by: Jassi Brar <[e-mail]>

drivers/mailbox/mtk-cmdq-mailbox.c

···
 				cmdq->clocks[alias_id].id = clk_names[alias_id];
 				cmdq->clocks[alias_id].clk = of_clk_get(node, 0);
 				if (IS_ERR(cmdq->clocks[alias_id].clk)) {
+					of_node_put(node);
 					return dev_err_probe(dev,
 							     PTR_ERR(cmdq->clocks[alias_id].clk),
 							     "failed to get gce clk: %d\n",