geofence: add counter threshold for subsequent detections

src/modules/navigator/geofence_params.c

@@ -83,3 +83,14 @@ PARAM_DEFINE_INT32(GF_ALTMODE, 0);
  * @group Geofence
  */
 PARAM_DEFINE_INT32(GF_SOURCE, 0);
+
+/**
+ * Geofence counter limit
+ *
+ * Set how many subsequent position measurements outside of the fence are needed before geofence violation is triggered
+ *
+ * @min -1
+ * @max 10
+ * @group Geofence
+ */
+PARAM_DEFINE_INT32(GF_COUNT, -1);