Fixes for 3way call initialization deadlock and call transfer

1. Don't lock sub->parent always in brcm_indicate() - in call conference and call transfer initialization it may cause deadlock;
2. Don't lock ast channel in brcm_indicate() since it is always locked already;
3. Lock ast channel on setting rtp statistics;
4. Don't allow to process brcm_hangup before call conference started completely;
5. Fixup for call transfer - restore transfer_redirect()