Re-implement Format_frameSize(), to support non-power-of-2

Change-Id: I671bd4f03ce70de685770fd7992e2e023133c9b4
diff --git a/media/libnbaio/NBAIO.cpp b/media/libnbaio/NBAIO.cpp
index cfcd8b4..16e7df5 100644
--- a/media/libnbaio/NBAIO.cpp
+++ b/media/libnbaio/NBAIO.cpp
@@ -24,8 +24,7 @@
 
 size_t Format_frameSize(const NBAIO_Format& format)
 {
-    // FIXME The sample format is hard-coded to AUDIO_FORMAT_PCM_16_BIT
-    return Format_channelCount(format) * sizeof(short);
+    return format.mFrameSize;
 }
 
 int Format_frameBitShift(const NBAIO_Format& format)