Fixing unique id DEVICE_ID3 on STM32L0 and STM32L1

On STM32L0 and STM32L1, `DEVICE_ID3` points at a reserved memory location
instead of the third word of the 96-bit unique device ID. The USB serial
number string is therefore derived from only 64 bits of the ID plus a
constant, and **devices from the same production lot and wafer enumerate with
byte-identical USB serial numbers**.

Author: acseka360

libraries/USBDevice/inc/usbd_desc.h

@@ -28,7 +28,18 @@
   /* Exported constants --------------------------------------------------------*/
   #define  DEVICE_ID1                  (UID_BASE)
   #define  DEVICE_ID2                  (UID_BASE + 0x4U)
-  #define  DEVICE_ID3                  (UID_BASE + 0x8U)
+  /*
+  * On STM32L0 and STM32L1 the three unique-ID words are NOT contiguous:
+  * the reference manuals place bits 95:64 at offset 0x14, not 0x08
+  * (RM0376/RM0377/RM0367/RM0451 "Unique device ID registers (96 bits)",
+  * and RM0038 for STM32L1). UID_BASE + 0x8U is a reserved location there.
+  * ST's own HAL_GetUIDw2() already uses 0x14U for these two families.
+  */
+  #if defined(STM32L0xx) || defined(STM32L1xx)
+    #define  DEVICE_ID3                (UID_BASE + 0x14U)
+  #else
+    #define  DEVICE_ID3                (UID_BASE + 0x8U)
+  #endif
 
   /*
   * USB Billboard Class USER string desc Defines Template