Cards with identical PCI ids but no AC97 config in EEPROM do not have
the ac97 field initialized. We must check for this case to avoid kernel oops.
Signed-off-by: Pavel Hofman <pavel.hofman@ivitera.com>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>