video: of: display_timing: Don't yell if no timing node is present

There may be cases (like in panel-simple.c) where we have a sane
fallback if no timings are specified in the device tree.  Let's get
rid of the unconditional pr_err().  We can add error messages in
individual drivers if it makes sense.

NOTE: we'll still print errors if the node is present but there are
problems parsing the timings.

Fixes: b8a2948f ("drm/panel: simple: Add ability to override typical timing")
Reported-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190722182439.44844-3-dianders@chromium.org

drivers/video/of_display_timing.c

@@ -125,10 +125,8 @@ int of_get_display_timing(const struct device_node *np, const char *name,
 		return -EINVAL;
 
 	timing_np = of_get_child_by_name(np, name);
-	if (!timing_np) {
-		pr_err("%pOF: could not find node '%s'\n", np, name);
+	if (!timing_np)
 		return -ENOENT;
-	}
 
 	ret = of_parse_display_timing(timing_np, dt);