ALSA: ac97 - Fix missing NULL check in snd_ac97_cvol_new()

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=44721

Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/ac97/ac97_codec.c

@@ -1271,6 +1271,8 @@ static int snd_ac97_cvol_new(struct snd_card *card, char *name, int reg, unsigne
 		tmp.index = ac97->num;
 		kctl = snd_ctl_new1(&tmp, ac97);
 	}
+	if (!kctl)
+		return -ENOMEM;
 	if (reg >= AC97_PHONE && reg <= AC97_PCM)
 		set_tlv_db_scale(kctl, db_scale_5bit_12db_max);
 	else