media: mtk-vpu: fix leaked of_node references

The call to of_parse_phandle returns a node pointer with refcount
incremented thus it must be explicitly decremented after the last
usage.

Detected by coccinelle with the following warnings:
drivers/media/platform/mtk-vpu/mtk_vpu.c:477:1-7: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 464, but without a corresponding object release within this function.
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/mtk-vpu/mtk_vpu.c

@@ -468,9 +468,9 @@ struct platform_device *vpu_get_plat_device(struct platform_device *pdev)
 	}
 
 	vpu_pdev = of_find_device_by_node(vpu_node);
+	of_node_put(vpu_node);
 	if (WARN_ON(!vpu_pdev)) {
 		dev_err(dev, "vpu pdev failed\n");
-		of_node_put(vpu_node);
 		return NULL;
 	}