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>
        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");