gpu: drm: rockchip_drm_drv: add missing of_node_put after calling of_parse_phandle

of_node_put needs to be called when the device node which is got
from of_parse_phandle has finished using.

Cc: Mark Yao <mark.yao@rock-chips.com>
Cc: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: NPeter Chen <peter.chen@nxp.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1467684294-20111-2-git-send-email-peter.chen@nxp.com

drivers/gpu/drm/rockchip/rockchip_drm_drv.c

@@ -433,6 +433,7 @@ static int rockchip_drm_platform_probe(struct platform_device *pdev)
 			is_support_iommu = false;
 		}
 
+		of_node_put(iommu);
 		component_match_add(dev, &match, compare_of, port->parent);
 		of_node_put(port);
 	}