Timed parent selection timer trigger update

Changed Trigged timed parent selection from delay multiple 0.9-1.1 --> 1.0-1.2.
This will guarantee that we will allways wait iMin time to learn other candidate hear.

Change-Id: I4c6c16ba5d3c1d9868f35d583c30bffaf6b7b775

Author: Juha Heiskanen

source/RPL/rpl_upward.c

@@ -355,7 +355,7 @@ void rpl_instance_force_leaf(rpl_instance_t *instance)
 void rpl_instance_trigger_parent_selection(rpl_instance_t *instance, uint16_t delay)
 {
     if (instance->parent_selection_timer == 0 || instance->parent_selection_timer > delay) {
-        instance->parent_selection_timer = randLIB_randomise_base(delay, 0x7333, 0x8CCD) /* +/- 10% */;
+        instance->parent_selection_timer = randLIB_randomise_base(delay, 0x8000, 0x999A) /* Random between delay * 1.0-1.2 */;
         tr_debug("Timed parent triggered %u", instance->parent_selection_timer);
     }
 }