usb: dwc3-generic: Add clock initialization in child DT node

Same as the reset cotnrol, should add a clock initialization in child DT
node, if the glue node doesn't have any clocks.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Reviewed-by: Marek Vasut <marex@denx.de>

drivers/usb/dwc3/dwc3-generic.c

@@ -572,6 +572,12 @@ static int dwc3_glue_probe(struct udevice *dev)
 	if (ret)
 		return ret;
 
+	if (glue->clks.count == 0) {
+		ret = dwc3_glue_clk_init(child, glue);
+		if (ret)
+			return ret;
+	}
+
 	if (glue->resets.count == 0) {
 		ret = dwc3_glue_reset_init(child, glue);
 		if (ret)