Updated wi-sun BBR min hop rank increase to 196.

Now we change parent when 25% tarffic fail it was earlier 50% which is too much.

Change-Id: If9dc504b27ff6cd06aa3c5b88d00afd99589b4d5

Author: Juha Heiskanen

source/6LoWPAN/ws/ws_bbr_api.c

@@ -71,7 +71,7 @@ static rpl_dodag_conf_t rpl_conf = {
     .authentication = 0,
     .path_control_size = 7,
     .dag_max_rank_increase = 2048,
-    .min_hop_rank_increase = 256,
+    .min_hop_rank_increase = 196,
     // DIO configuration
     .dio_interval_min = WS_RPL_DIO_IMIN,
     .dio_interval_doublings = WS_RPL_DIO_DOUBLING,