drm/tegra: checking for IS_ERR() instead of NULL

The tegra_sor_hdmi_find_settings() function returns NULL on error and
not an ERR_PTR.

Fixes: 459cc2c6800b ('drm/tegra: sor: Add HDMI support')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/sor.c

@@ -1946,9 +1946,9 @@ static void tegra_sor_hdmi_enable(struct drm_encoder *encoder)
 
 	/* production settings */
 	settings = tegra_sor_hdmi_find_settings(sor, mode->clock * 1000);
-	if (IS_ERR(settings)) {
-		dev_err(sor->dev, "no settings for pixel clock %d Hz: %ld\n",
-			mode->clock * 1000, PTR_ERR(settings));
+	if (!settings) {
+		dev_err(sor->dev, "no settings for pixel clock %d Hz\n",
+			mode->clock * 1000);
 		return;
 	}