bluetooth: nrf52: Use the own LTK key for LESC pairing

Fix the issue that reconnection fails when LESC bonding information
is stored. For LESC pairing, it should use own LTK instead of peer one.

sdk/modules/bluetooth/hal/nrf52/ble_comm.c

@@ -3386,7 +3386,18 @@ static int nrf52_ble_pairing(uint16_t handle)
        * skip pairing and only encrypt with stored key.
        */
 
-      ret = BLE_GapEncrypt(handle, &BondInfoInFlash[ret].peerEncKey);
+      if (BondInfoInFlash[ret].ownEncKey.master_id.ediv != 0)
+        {
+          /* LE Legacy Pairing */
+
+          ret = BLE_GapEncrypt(handle, &BondInfoInFlash[ret].peerEncKey);
+        }
+      else
+        {
+          /* LE Secure Connections Pairing */
+
+          ret = BLE_GapEncrypt(handle, &BondInfoInFlash[ret].ownEncKey);
+        }
     }
   else
     {