[Silicon Labs] Update board IDs

Updated board IDs for Silicon Labs targets.

Author: stevew817

mbed_lstools/lstools_base.py

@@ -215,6 +215,9 @@ def __init__(self, **kwargs):
         "2025": "EFM32TG_STK3300",
         "2030": "EFM32ZG_STK3200",
         "2035": "EFM32PG_STK3401",
+        "2040": "EFM32PG12_STK3402",
+        "2041": "THUNDERBOARD_SENSE_12",
+        "2045": "THUNDERBOARD_SENSE",
         "2100": "XBED_LPC1768",
         "2201": "WIZWIKI_W7500",
         "2202": "WIZWIKI_W7500ECO",