drm/omap: print error instead of WARN() if plane setup fails

omap_plane_atomic_update() does WARN_ON() if dispc rejects the given
plane config. Change that to dev_err() to lessen the possible spam.

To fix this correctly, the plane setup needs much more work by creating
a check function for dispc setup, so that we could reliably check the
config in atomic_check, instead of only noticing the problem when
programming dispc.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/gpu/drm/omapdrm/omap_plane.c

@@ -131,7 +131,9 @@ static void omap_plane_atomic_update(struct drm_plane *plane,
 	/* and finally, update omapdss: */
 	ret = dispc_ovl_setup(omap_plane->id, &info, false,
 			      omap_crtc_timings(state->crtc), false);
-	if (WARN_ON(ret)) {
+	if (ret) {
+		dev_err(plane->dev->dev, "Failed to setup plane %s\n",
+			omap_plane->name);
 		dispc_ovl_enable(omap_plane->id, false);
 		return;
 	}