drm/omap: output: use dev_err instead of DSSERR

We don't have omapdss's custom error printing functions in the common
omapdss-base module, to which we want to move output.c.

This patch changes output.c to use dev_err instead of DSSERR so that it
doesn't depend on DSSERR.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

drivers/gpu/drm/omapdrm/dss/output.c

@@ -35,14 +35,15 @@ int omapdss_output_set_device(struct omap_dss_device *out,
 	mutex_lock(&output_lock);
 
 	if (out->dst) {
-		DSSERR("output already has device %s connected to it\n",
+		dev_err(out->dev,
+			"output already has device %s connected to it\n",
 			out->dst->name);
 		r = -EINVAL;
 		goto err;
 	}
 
 	if (out->output_type != dssdev->type) {
-		DSSERR("output type and display type don't match\n");
+		dev_err(out->dev, "output type and display type don't match\n");
 		r = -EINVAL;
 		goto err;
 	}
@@ -67,13 +68,15 @@ int omapdss_output_unset_device(struct omap_dss_device *out)
 	mutex_lock(&output_lock);
 
 	if (!out->dst) {
-		DSSERR("output doesn't have a device connected to it\n");
+		dev_err(out->dev,
+			"output doesn't have a device connected to it\n");
 		r = -EINVAL;
 		goto err;
 	}
 
 	if (out->dst->state != OMAP_DSS_DISPLAY_DISABLED) {
-		DSSERR("device %s is not disabled, cannot unset device\n",
+		dev_err(out->dev,
+			"device %s is not disabled, cannot unset device\n",
 			out->dst->name);
 		r = -EINVAL;
 		goto err;