usb: musb: dsps: control musb speed based on dts setting

Set musb config->maximum_speed based on the dts setting to control musb
speed.

By default musb works in high-speed mode. Adding

	maximum-speed = "full-speed";

to dts usb node will force musb to full-speed mode.
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/musb/musb_dsps.c

@@ -747,6 +747,19 @@ static int dsps_create_musb_pdev(struct dsps_glue *glue,
 	if (!ret && val)
 		config->multipoint = true;
 
+	config->maximum_speed = of_usb_get_maximum_speed(dn);
+	switch (config->maximum_speed) {
+	case USB_SPEED_LOW:
+	case USB_SPEED_FULL:
+		break;
+	case USB_SPEED_SUPER:
+		dev_warn(dev, "ignore incorrect maximum_speed "
+				"(super-speed) setting in dts");
+		/* fall through */
+	default:
+		config->maximum_speed = USB_SPEED_HIGH;
+	}
+
 	ret = platform_device_add_data(musb, &pdata, sizeof(pdata));
 	if (ret) {
 		dev_err(dev, "failed to add platform_data\n");