audio-hal: close stream even if stream stop failed in AudioStream::standby()

Currently, in AudioStream::standby(), if stream stop failed and standby
did not complete. For next Write, we will try to write to the stream
which we intend to cleanup before.

Deleting "goto exit" statement in the stream stop check block, so that
stream would be closed.

Change-Id: Ib759c1896ea1f205be49e5536ad2a39a2c39fdaf