ALSA: ice1712: Save/restore routing and rate registers

Save/restore routing and rate registers during suspend/resume.
This fixes S/PDIF input being disabled after resume.
Tested with Audiophile 24/96.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>