hal: bug fixes for PCM offload

When pcm offload is done, override the buffer size
that was calculated and use the value from the system property
Make write call blocking if small buffers are used in offload
Update latency value for pcm offload with small buffer hint based
on period size and period count.

Change-Id: Ic74caa6bd172c8e4554384e9fa98a5137117f07c
diff --git a/hal/audio_hw.h b/hal/audio_hw.h
index 3340230..818389a 100644
--- a/hal/audio_hw.h
+++ b/hal/audio_hw.h
@@ -181,6 +181,7 @@
     struct stream_app_type_cfg app_type_cfg;
 
     int non_blocking;
+    bool use_small_bufs;
     int playback_started;
     int offload_state;
     pthread_cond_t offload_cond;