Merge pull request #220 from cyliangtw/IoT_M252

Update M252 platform name

Author: mark-edgeworth

src/mbed_os_tools/detect/platform_database.py

@@ -239,7 +239,7 @@
         u"1306": u"NUMAKER_PFM_NANO130",
         u"1307": u"NUMAKER_PFM_NUC240",
         u"1308": u"NUMAKER_IOT_M487",
-        u"1309": u"NUMAKER_M252KG",
+        u"1309": u"NUMAKER_IOT_M252",
         u"1310": u"NUMAKER_IOT_M263A",
         u"1312": u"NU_M2354",
         u"1500": u"RHOMBIO_L476DMW1K",