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/printer.c b/drivers/usb/gadget/printer.c
index 65a8834..b74f49ac 100644
--- a/drivers/usb/gadget/printer.c
+++ b/drivers/usb/gadget/printer.c
@@ -1141,7 +1141,7 @@
 				break;
 #ifdef CONFIG_USB_GADGET_DUALSPEED
 			case USB_DT_DEVICE_QUALIFIER:
-				if (!gadget->is_dualspeed)
+				if (!gadget_is_dualspeed(gadget))
 					break;
 				/*
 				 * assumes ep0 uses the same value for both
@@ -1155,7 +1155,7 @@
 				break;
 
 			case USB_DT_OTHER_SPEED_CONFIG:
-				if (!gadget->is_dualspeed)
+				if (!gadget_is_dualspeed(gadget))
 					break;
 				/* FALLTHROUGH */
 #endif /* CONFIG_USB_GADGET_DUALSPEED */