[ALSA] sun-cs4231: memory management fix

The chip structure is now allocated by snd_card_new()
and it must not be released by separate kfree().

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>