Wi-sun Discovery update:

Enter Discovery state bootstrap remove old keys from PAE Controller

Removed Unnecessary key remove at Config learn reach MAX solication TX state.

Change-Id: I073aaabfdcd1b88ff980530cf03b4a3209b4686a

Author: Juha Heiskanen

source/6LoWPAN/ws/ws_bootstrap.c

@@ -2229,6 +2229,8 @@ static void ws_bootstrap_pan_version_increment(protocol_interface_info_entry_t *
 static void ws_bootstrap_start_discovery(protocol_interface_info_entry_t *cur)
 {
     tr_debug("router discovery start");
+    // Remove network keys from MAC
+    ws_pae_controller_nw_keys_remove(cur);
     ws_bootstrap_state_change(cur, ER_ACTIVE_SCAN);
     cur->nwk_nd_re_scan_count = 0;
     cur->ws_info->configuration_learned = false;
@@ -2861,9 +2863,6 @@ void ws_bootstrap_trickle_timer(protocol_interface_info_entry_t *cur, uint16_t t
         if (cur->ws_info->pas_requests >= PCS_MAX) {
             // if MAX PCS sent restart discovery
 
-            // Remove network keys from MAC
-            ws_pae_controller_nw_keys_remove(cur);
-
             // Trickle is reseted when entering to discovery from state 3
             trickle_inconsistent_heard(&cur->ws_info->trickle_pan_advertisement_solicit, &cur->ws_info->trickle_params_pan_discovery);
             ws_bootstrap_event_discovery_start(cur);