Remove ML_DEBUG_PRINT config flag from pxt.json.

So that user programmes can add it later in their pxt.json file
from the MakeCode editor.

Author: microbit-carlos

pxt.json

@@ -33,8 +33,7 @@
     "yotta": {
         "config": {
             "ML_INFERENCE_PERIOD_MS": 250,
-            "ML_EVENT_LISTENER_DEFAULT_FLAGS": 32,
-            "ML_DEBUG_PRINT": 0
+            "ML_EVENT_LISTENER_DEFAULT_FLAGS": 32
         }
     }
 }