ALSA: aaci - Fix NULL test at error path

The original fix by Julien Brunel <brunel@diku.dk>.

aaci_init_card() returns a pointer with ERR_PTR(), but in aaci_init()
NULL is supposed at this error path.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>