pcm: hw: add an arrangement for initialization of appl_ptr/avail_min

pcm: hw: add an arrangement for initialization of appl_ptr/avail_min

Regardless of success/failure mapping of control/status data for runtime of
PCM substream, appl_ptr/avail_min parameters are initialized. In current
implementation, they are initialized in case-dependent, different places.
It's possible to collect them to one place.

This commit unifies relevant code in a place after all of trials for the
mappings are finished.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>