usb: dwc2: Add original Synopsys compat string

Add the Synopsys compatible string. This is used in SoCFPGA DT files.

Signed-off-by: Marek Vasut <marex@denx.de>

drivers/usb/host/dwc2.c

@@ -1113,6 +1113,7 @@ struct dm_usb_ops dwc2_usb_ops = {
 
 static const struct udevice_id dwc2_usb_ids[] = {
 	{ .compatible = "brcm,bcm2835-usb" },
+	{ .compatible = "snps,dwc2" },
 	{ }
 };