timer: mtk: skip setting parent with dummy fixed-clock

Skip setting parent with dummy fixed-clock. Upstream linux might declare
an additional clock for the mtk timer and that additional clock might
also be a fixed-clock defined in DT. Setting parent of a dummy fixed-clock
resulta in error hence mtk timer fails to probe.

Skip setting parent to permit correct probe of the mtk timer.

Fixes: d3c3606c5c ("timer: MediaTek: add timer driver for MediaTek SoCs")
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

drivers/timer/mtk_timer.c

@@ -73,7 +73,8 @@ static int mtk_timer_probe(struct udevice *dev)
 		return ret;
 
 	ret = clk_get_by_index(dev, 1, &parent);
-	if (!ret) {
+	/* Skip setting the parent with dummy fixed-clock */
+	if (!ret && parent.dev->driver != DM_DRIVER_GET(fixed_clock)) {
 		ret = clk_set_parent(&clk, &parent);
 		if (ret)
 			return ret;