Fixed the restore of pin configs at resume for some STAC/IDT codec
models.  These models set explicitly the pin configs after the default
init configs, and these aren't restored properly at resume.

This patch introduces two changes:
- Allocate always pin_configs array in stac_spec so that the driver
  can overwrite the value freely
- Introduce stac_change_pin_config() to change the pin config value
Signed-off-by: NTakashi Iwai <tiwai@suse.de>