ALSA: pcm: add locks for accessing runtime resource

Add spin lock to resolve race conditions while
accessing substream runtime resource

CRs-fixed: 2112713
Change-Id: I8db743303ceb50205d62adfc02caf6ecab635d47
Signed-off-by: Karthikeyan Mani <kmani@codeaurora.org>

include/sound/pcm.h

@@ -399,6 +399,7 @@ struct snd_pcm_substream {
 	struct snd_pcm_ops *ops;
 	/* -- runtime information -- */
 	struct snd_pcm_runtime *runtime;
+	spinlock_t runtime_lock;
         /* -- timer section -- */
 	struct snd_timer *timer;		/* timer */
 	unsigned timer_running: 1;	/* time is running */