Clean up ice1712/ice1724 codes.  The board-specific data is allocated
locally in each code instead of having an ungly union in struct ice1712.
Also, fix coding issues in prodigy_hifi.c.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@perex.cz>