usb: gadget: replace usb_gadget::is_dualspeed with max_speed

This commit replaces usb_gadget's is_dualspeed field with
a max_speed field.

[ balbi@ti.com : Fixed DWC3 driver ]

Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/gadget/amd5536udc.c b/drivers/usb/gadget/amd5536udc.c
index 45f422a..e69cdbc 100644
--- a/drivers/usb/gadget/amd5536udc.c
+++ b/drivers/usb/gadget/amd5536udc.c
@@ -3349,7 +3349,7 @@
 	dev_set_name(&dev->gadget.dev, "gadget");
 	dev->gadget.dev.release = gadget_release;
 	dev->gadget.name = name;
-	dev->gadget.is_dualspeed = 1;
+	dev->gadget.max_speed = USB_SPEED_HIGH;
 
 	/* init registers, interrupts, ... */
 	startup_registers(dev);