When a codec is powered off, some systems don't respond properly after
D3 FG transition, while the driver still expects the response and
tries to fall back to different modes (polling and single-cmd).  When
the fallback happens, the driver stays in that mode, and falling back
to the single-cmd mode means it'll loose the unsol event handling,
too.

The unresponsiveness at D3 isn't too serious, thus this fallback is
mostly superfluous.  We can gracefully ignore the error there so that
the driver keeps the normal operation mode.

This patch adds a new bit flag for codec read/write, set in the power
transition stage, which is notified to the controller driver via a new
bus->no_response_fallback flag.
Signed-off-by: Takashi Iwai <tiwai@suse.de>