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/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c
index 922148f..47a3d1e 100644
--- a/drivers/usb/musb/musb_gadget.c
+++ b/drivers/usb/musb/musb_gadget.c
@@ -1844,7 +1844,7 @@
 	 */
 
 	musb->g.ops = &musb_gadget_operations;
-	musb->g.is_dualspeed = 1;
+	musb->g.max_speed = USB_SPEED_HIGH;
 	musb->g.speed = USB_SPEED_UNKNOWN;
 
 	/* this "gadget" abstracts/virtualizes the controller */