ALSA: PCM: Remove redundant null check before kfree

kfree on a null pointer is a no-op.
Signed-off-by: NSachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/core/pcm.c

@@ -981,8 +981,7 @@ void snd_pcm_detach_substream(struct snd_pcm_substream *substream)
 		       PAGE_ALIGN(sizeof(struct snd_pcm_mmap_control)));
 	kfree(runtime->hw_constraints.rules);
 #ifdef CONFIG_SND_PCM_XRUN_DEBUG
-	if (runtime->hwptr_log)
-		kfree(runtime->hwptr_log);
+	kfree(runtime->hwptr_log);
 #endif
 	kfree(runtime);
 	substream->runtime = NULL;