atrace: fix duplicate tag 'sync'

Recent AOSP commit added a tag 'sync' for ATRACE_TAG_SYNC_MANAGER but
the tag 'sync' was already being used for "Synchronization" events.

Due to this conflict, the Synchronization events are not enabled
anymore with the name duplication. To avoid this,'sync' for
sync_manager is renamed to 'sm'

Change-Id: Ieb7b504e63f0eadc8d889af9cfed217287c75a6b
diff --git a/cmds/atrace/atrace.cpp b/cmds/atrace/atrace.cpp
index 9e5c910..a92f438 100644
--- a/cmds/atrace/atrace.cpp
+++ b/cmds/atrace/atrace.cpp
@@ -77,7 +77,7 @@
     { "webview",    "WebView",          ATRACE_TAG_WEBVIEW, { } },
     { "wm",         "Window Manager",   ATRACE_TAG_WINDOW_MANAGER, { } },
     { "am",         "Activity Manager", ATRACE_TAG_ACTIVITY_MANAGER, { } },
-    { "sync",       "Sync Manager",     ATRACE_TAG_SYNC_MANAGER, { } },
+    { "sm",       "Sync Manager",     ATRACE_TAG_SYNC_MANAGER, { } },
     { "audio",      "Audio",            ATRACE_TAG_AUDIO, { } },
     { "video",      "Video",            ATRACE_TAG_VIDEO, { } },
     { "camera",     "Camera",           ATRACE_TAG_CAMERA, { } },