audio: Fix memory leak

Free command object queued with offload_thread_loop
when driving instance is unavailable.

Change-Id: I310a462ae8efe707658d941e88cb5ea59a9f8550
CRs-Fixed: 1022145
diff --git a/hal/audio_hw.c b/hal/audio_hw.c
index 55b0cc7..17f71cc 100644
--- a/hal/audio_hw.c
+++ b/hal/audio_hw.c
@@ -1494,6 +1494,7 @@
 
         if (out->compr == NULL) {
             ALOGE("%s: Compress handle is NULL", __func__);
+            free(cmd);
             pthread_cond_signal(&out->cond);
             continue;
         }