ALSA: dice: cache stream formats at current mode of sampling transmission frequency

In former commits, proxy structure get members for cache of stream
formats. This commit fills the cache with stream formats at current mode
of sampling transmission frequency.

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