[ARM] tegra_i2s_audio: fixes

[ARM] tegra_i2s_audio: fixes

-- Ignore kfifo thresholds on recording and playback and adjust the delays.
-- Take out the code from TEGRA_AUDIO_IN_STOP into a separate function
   stop_recording_nosync()
-- Rename stop_recording() to wait_for_recording_to_stop().
-- add ioctl(TEGRA_AUDIO_OUT_FLUSH), which blocks the caller until the output
   fifo is drained.  While the caller is blocked, pending write() calls will
   return immediately with whatever data they had managed to queue up.
-- removed ioctl(TEGRA_AUDIO_OUT_PRELOAD_FIFO)
-- since TEGRA_AUDIO_OUT_FLUSH and TEGRA_AUDIO_IN_STOP act similarly, moved
   audio_driver_state::recording_cancelled to audio_stream::stop and changed
   the code accordingly.  Renamed functions wait_for_recording_to_stop() and
   stop_recording_nosync() to wait_till_stopped() and request_stop_nosync()
   since they handle both playback and recording.
-- print errors on close() if wakelocks are still held
-- Call request_stop_nosync() on close() of a recording file handle
-- Do not use struct audio_stream::active for playback streams.  Instead,
   where applicable, use kfifo_len().  As a consequence, playback kfifo
   underruns are no longer reported.  These were bogus anyway, as we really
   need the DMA engine to tell us if there are underruns.
-- Because of above item, had to rework tx_fifo_atn_store(),
   rx_fifo_atn_store(), and __attr_fifo_atn_write().
-- Set struct audio_stream::active for a recording stream to true when a
   recording starts, and set it to false when recording get stopped.  Do not
   set/clear it within the body of read(), because just being within read()
   does not mean that recording is in progress.
-- In tegra_audio_read(), check for stop == true before calling
   start_recording_if_necessary(); this makes sure that if a user calls read()
   after calling ioctl(TEGRA_AUDIO_IN_STOP), recording will not resume unless
   ioctl(TEGRA_AUDIO_IN_START) gets called, or the file is closed and
   re-opened.
-- Fixed TEGRA_AUDIO_IN_START
-- In PIO mode, enabled FIFOs before enabling interrupts as specified in the
   TRM.
-- Added missing break in tegra_audio_ioctl().
-- Silenced some debug spew

Signed-off-by: Iliyan Malchev <malchev@google.com>