Use audio_format_t consistently

Was int, uint32_t, uint16_t, and uint8_t with 2-bit bitfield.
Also replace 0 by AUDIO_FORMAT_DEFAULT and replace 1 by
AUDIO_FORMAT_PCM_16_BIT.

Change-Id: Ia8804f53f1725669e368857d5bb2044917e17975
diff --git a/include/media/MediaPlayerInterface.h b/include/media/MediaPlayerInterface.h
index 80f43a3..1f6bdda 100644
--- a/include/media/MediaPlayerInterface.h
+++ b/include/media/MediaPlayerInterface.h
@@ -85,7 +85,7 @@
         // audio data.
         virtual status_t    open(
                 uint32_t sampleRate, int channelCount,
-                int format=AUDIO_FORMAT_PCM_16_BIT,
+                audio_format_t format=AUDIO_FORMAT_PCM_16_BIT,
                 int bufferCount=DEFAULT_AUDIOSINK_BUFFERCOUNT,
                 AudioCallback cb = NULL,
                 void *cookie = NULL) = 0;