Merge pull request #10140 from Bob-the-Kuhn/DUE-full-speed

[2.0.x] DUE - add full speed USB native port option

Marlin/src/HAL/HAL_DUE/usb/conf_usb.h

 //! To define a Low speed device
 //#define  USB_DEVICE_LOW_SPEED
 
+//! To define a Full speed device
+//#define  USB_DEVICE_FULL_SPEED
+
 //! To authorize the High speed
-#if (UC3A3||UC3A4)
-#  define  USB_DEVICE_HS_SUPPORT
-#elif (SAM3XA||SAM3U)
-#  define  USB_DEVICE_HS_SUPPORT
+#ifndef USB_DEVICE_FULL_SPEED
+  #if (UC3A3||UC3A4)
+    #define  USB_DEVICE_HS_SUPPORT
+  #elif (SAM3XA||SAM3U)
+    #define  USB_DEVICE_HS_SUPPORT
+  #endif
 #endif
 //@}