drm/mcde: dsi: Fix return value check in mcde_dsi_bind()

The of_drm_find_bridge() function returns NULL on error, it doesn't return
error pointers so this check doesn't work.

Fixes: 5fc537bf ("drm/mcde: Add new driver for ST-Ericsson MCDE")
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200430073145.52321-1-weiyongjun1@huawei.com

drivers/gpu/drm/mcde/mcde_dsi.c

@@ -1073,10 +1073,9 @@ static int mcde_dsi_bind(struct device *dev, struct device *master,
 			panel = NULL;
 
 			bridge = of_drm_find_bridge(child);
-			if (IS_ERR(bridge)) {
-				dev_err(dev, "failed to find bridge (%ld)\n",
-					PTR_ERR(bridge));
-				return PTR_ERR(bridge);
+			if (!bridge) {
+				dev_err(dev, "failed to find bridge\n");
+				return -EINVAL;
 			}
 		}
 	}