usb: gadget: mv_udc: set is_dualspeed = 1

This controller support full and high speed.

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
diff --git a/drivers/usb/gadget/mv_udc.c b/drivers/usb/gadget/mv_udc.c
index 7bf70d1..0a19dce 100644
--- a/drivers/usb/gadget/mv_udc.c
+++ b/drivers/usb/gadget/mv_udc.c
@@ -107,6 +107,7 @@
 	.gadget	= {
 		.name	= "mv_udc",
 		.ops	= &mv_udc_ops,
+		.is_dualspeed = 1,
 	},
 };