ALSA: ali5451: Drop unused variable

The variable runtime is never used, and this might be even a source of
NULL-dereference. Nothing better than killing it.

Spotted by coverity CID 100862.

Signed-off-by: Takashi Iwai <[e-mail]>

sound/pci/ali5451/ali5451.c

···
 static void snd_ali_update_ptr(struct snd_ali *codec, int channel)
 {
 	struct snd_ali_voice *pvoice;
-	struct snd_pcm_runtime *runtime;
 	struct snd_ali_channel_control *pchregs;
 	unsigned int old, mask;
 #ifdef ALI_DEBUG
···
 		return;
 
 	pvoice = &codec->synth.voices[channel];
-	runtime = pvoice->substream->runtime;
 
 	udelay(100);
 	spin_lock(&codec->reg_lock);