FastMixerState was missing a LOG_TAG

Test: logs in FastMixerState module have the correct tag
Change-Id: Id38826754e35803a72376a9198d2839fe195b0b2
diff --git a/services/audioflinger/FastMixerState.cpp b/services/audioflinger/FastMixerState.cpp
index ad471fb..36d8eef 100644
--- a/services/audioflinger/FastMixerState.cpp
+++ b/services/audioflinger/FastMixerState.cpp
@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+#define LOG_TAG "FastMixerState"
+//#define LOG_NDEBUG 0
+
 #include <cutils/properties.h>
 #include "FastMixerState.h"