ALSA: iec1712: Initialize STDSP24 properly when using the model=staudio option

ALSA: iec1712: Initialize STDSP24 properly when using the model=staudio option

The ST Audio ADCIII is an STDSP24 card plus extension box. With commit
e8a91ae18bdc ("ALSA: ice1712: Add support for STAudio ADCIII") we
enabled the ADCIII ports using the model=staudio option but forgot
this part to ensure the STDSP24 card is initialized properly.

Fixes: e8a91ae18bdc ("ALSA: ice1712: Add support for STAudio ADCIII")
Signed-off-by: Scott Bahling <sbahling@suse.com>
Cc: <stable@vger.kernel.org>
BugLink: https://bugzilla.suse.com/show_bug.cgi?id=1048934
Link: https://lore.kernel.org/r/20200518175728.28766-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>