add LittleFS part ID

Author: Jason2866

Diff for: tools/gen_esp32part.py

@@ -71,6 +71,7 @@ def get_ptype_as_int(ptype):
         'esphttpd': 0x80,
         'fat': 0x81,
         'spiffs': 0x82,
+        'littlefs': 0x83,
     },
 }