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: b8a2948fa2b3 ("drm/panel: simple: Add ability to override typical timing")
Reported-by: Sam Ravnborg <[e-mail]>
Signed-off-by: Douglas Anderson <[e-mail]>
Reviewed-by: Sam Ravnborg <[e-mail]>
Cc: Thierry Reding <[e-mail]>
Cc: David Airlie <[e-mail]>
Cc: Philipp Zabel <[e-mail]>
Cc: Tomi Valkeinen <[e-mail]>
Cc: Laurent Pinchart <[e-mail]>
Cc: Russell King <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Signed-off-by: Bartlomiej Zolnierkiewicz <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/video/of_display_timing.c

···
 		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);