ASoC: msm: Fix subsystem restart crash.

-Subsystem restart attempts made back to back
results in crash.
-Accessing Null pointer while subsystem restart
in progress.
-Update the afe_callback function to return
after processing the RESET_EVENTS.

Change-Id: I53f0fecd6079d1788dc7cc5a2587383da9901084
Signed-off-by: Laxminath Kasam <lkasam@codeaurora.org>
diff --git a/sound/soc/msm/qdsp6/q6afe.c b/sound/soc/msm/qdsp6/q6afe.c
index 21bbcf2..74a66945 100644
--- a/sound/soc/msm/qdsp6/q6afe.c
+++ b/sound/soc/msm/qdsp6/q6afe.c
@@ -56,6 +56,7 @@
 		pr_debug("task_name = %s pid = %d\n",
 			this_afe.task->comm, this_afe.task->pid);
 		send_sig(SIGUSR1, this_afe.task, 0);
+		return 0;
 	}
 	if (data->payload_size) {
 		uint32_t *payload;