Fix missing tag in mediaserver ServiceManager: log

Change-Id: I2d5525ffee0b66c0bc361a02b313ec4dd61e6552
diff --git a/media/mediaserver/main_mediaserver.cpp b/media/mediaserver/main_mediaserver.cpp
index b5f85f9..54e77ef 100644
--- a/media/mediaserver/main_mediaserver.cpp
+++ b/media/mediaserver/main_mediaserver.cpp
@@ -15,6 +15,8 @@
 ** limitations under the License.
 */
 
+#define LOG_TAG "mediaserver"
+
 #include <binder/IPCThreadState.h>
 #include <binder/ProcessState.h>
 #include <binder/IServiceManager.h>