AudioFlinger: rename variables to clarify reference to track channel count or channel mask

Some variables and structure members should be renamed to reflect the fact that they contain the
number of channels in a track (channel count) or the actual channels used by a track (channel mask).
Especially member "channels" of track control block (struct audio_track_cblk_t) is actually the
number of channels (channels count).

Change-Id: I220c8dede9fc00c8a5693389e790073b6ed307b8
diff --git a/libs/audioflinger/AudioFlinger.h b/libs/audioflinger/AudioFlinger.h
index 13aac8b..c4a5305 100644
--- a/libs/audioflinger/AudioFlinger.h
+++ b/libs/audioflinger/AudioFlinger.h
@@ -366,9 +366,10 @@
                     sp<AudioFlinger>        mAudioFlinger;
                     uint32_t                mSampleRate;
                     size_t                  mFrameCount;
-                    int                     mChannelCount;
+                    uint32_t                mChannels;
+                    uint16_t                mChannelCount;
+                    uint16_t                mFrameSize;
                     int                     mFormat;
-                    uint32_t                mFrameSize;
                     Condition               mParamCond;
                     Vector<String8>         mNewParameters;
                     status_t                mParamStatus;