nimble/ll: Fix RPA address in the LE Enhanced Connection Complete

It solves following issue:

Scenario:
1. Nimble has peer device in the resolving list.
2. Peer device is in Device Privacy Mode
3. Peer device is using its RPA and our identity address as InitA in
directed advertising on which Nimble send Connect Ind with its identity address

Issue:
Nimble incorretly set Local RPA address in the LE Enhanced Connect Completed event.

This should fix: LL/CON/INI/BV-10-C and LL/CON/INI/BV-21-C

nimble/controller/include/controller/ble_ll_conn.h

@@ -269,6 +269,12 @@ struct ble_ll_conn_sm
     uint32_t slave_cur_window_widening;
     uint32_t last_rxd_pdu_cputime;  /* Used exclusively for supervision timer */
 
+    /*
+     * Used to mark that direct advertising from the peer was using
+     * identity address as InitA
+     */
+    uint8_t inita_identity_used;
+
     /* address information */
     uint8_t own_addr_type;
     uint8_t peer_addr_type;

nimble/controller/src/ble_ll_conn.c

@@ -849,6 +849,8 @@ ble_ll_conn_init_wfr_timer_exp(void)
         STATS_INC(ble_ll_stats, aux_missed_adv);
         ble_ll_event_send(&scansm->scan_sched_ev);
     }
+
+    connsm->inita_identity_used = 0;
 #endif
 }
 /**
@@ -3456,6 +3458,10 @@ ble_ll_init_rx_isr_end(uint8_t *rxbuf, uint8_t crcok,
         goto init_rx_isr_exit;
     }
 
+    if (init_addr && !inita_is_rpa) {
+        connsm->inita_identity_used = 1;
+    }
+
     CONN_F_CONN_REQ_TXD(connsm) = 1;
 
 #if MYNEWT_VAL(BLE_LL_CFG_FEAT_LL_EXT_ADV)

nimble/controller/src/ble_ll_conn_hci.c

@@ -163,7 +163,13 @@ ble_ll_conn_comp_event_send(struct ble_ll_conn_sm *connsm, uint8_t status,
             if (enh_enabled) {
                 memset(evdata, 0, 2 * BLE_DEV_ADDR_LEN);
                 if (connsm->conn_role == BLE_LL_CONN_ROLE_MASTER) {
-                    if (connsm->own_addr_type > BLE_HCI_ADV_OWN_ADDR_RANDOM) {
+                    if (connsm->inita_identity_used) {
+                        /* If it was direct advertising we were replying to and we used
+                         * identity address there (which might be just fine), we should
+                         * we should take it into account here in this event.
+                         */
+                        rpa = NULL;
+                    } else  if (connsm->own_addr_type > BLE_HCI_ADV_OWN_ADDR_RANDOM) {
                         rpa = ble_ll_scan_get_local_rpa();
                     } else {
                         rpa = NULL;