hal: Avoid double free while closing of VoIP driver

There is a double free happening while closing of VoIP
driver using passthrough apk. There is no protection of
VoIP node during close of  VoIP driver. Add protection
to avoid double free of VoIP node

Change-Id: I54c2a6aec525590e3e6782d356168f8fe8dc86b0
1 file changed