ALSA: sb: fix a missing check of snd_ctl_add

snd_ctl_add() could fail, so let's check its return value and return its
error code upstream upon failure.
Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/isa/sb/sb16_main.c

@@ -879,10 +879,14 @@ int snd_sb16dsp_pcm(struct snd_sb *chip, int device)
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_sb16_playback_ops);
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_sb16_capture_ops);
 
-	if (chip->dma16 >= 0 && chip->dma8 != chip->dma16)
-		snd_ctl_add(card, snd_ctl_new1(&snd_sb16_dma_control, chip));
-	else
+	if (chip->dma16 >= 0 && chip->dma8 != chip->dma16) {
+		err = snd_ctl_add(card, snd_ctl_new1(
+					&snd_sb16_dma_control, chip));
+		if (err)
+			return err;
+	} else {
 		pcm->info_flags = SNDRV_PCM_INFO_HALF_DUPLEX;
+	}
 
 	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV,
 					      snd_dma_isa_data(),