alif/usbd: Implement proper USB serial number.

Using SE services to get the SoC unique id.

Signed-off-by: Damien George <damien@micropython.org>

Author: dpgeorge

ports/alif/usbd.c

@@ -30,10 +30,11 @@
 
 #include "shared/tinyusb/mp_usbd.h"
 #include "tusb.h"
+#include "se_services.h"
 
 void mp_usbd_port_get_serial_number(char *serial_buf) {
-    // TODO
-    uint8_t id[8] = "ABCDEFGH";
+    uint8_t id[5];
+    se_services_get_unique_id(id);
     MP_STATIC_ASSERT(sizeof(id) * 2 <= MICROPY_HW_USB_DESC_STR_MAX);
     mp_usbd_hex_str(serial_buf, id, sizeof(id));
 }