drm/rockchip: analogix_dp: drop unnecessary probe deferral "error" print

This driver is the only user of of_drm_find_panel() which prints an
error before doing probe deferral, yielding messages like this on boot,
before eventually succeeding:

[    2.234271] [drm:rockchip_dp_probe] *ERROR* failed to find panel
...
[    4.797539] [drm:rockchip_dp_probe] *ERROR* failed to find panel
...

Let's just drop the message.
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>

drivers/gpu/drm/rockchip/analogix_dp-rockchip.c

@@ -447,10 +447,8 @@ static int rockchip_dp_probe(struct platform_device *pdev)
 
 		panel = of_drm_find_panel(panel_node);
 		of_node_put(panel_node);
-		if (!panel) {
-			DRM_ERROR("failed to find panel\n");
+		if (!panel)
 			return -EPROBE_DEFER;
-		}
 	}
 
 	dp = devm_kzalloc(dev, sizeof(*dp), GFP_KERNEL);