ALSA: ice1724 - Support for multiple external clock types

* Support for customization of the external clock names
* Adding hooks to playback_pro_open and capture_pro_open, allowing e.g.
  limiting available stream rates to a single value when the external
  clock rate is detected

Signed-off-by: Pavel Hofman <pavel.hofman@ivitera.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>