Add trace tag for power management.

Bug: 17004602
Change-Id: Iecd79e6e0417c02b902cde468b0e842f9348b386
diff --git a/include/cutils/trace.h b/include/cutils/trace.h
index fd9bc6a..fd24561 100644
--- a/include/cutils/trace.h
+++ b/include/cutils/trace.h
@@ -70,7 +70,8 @@
 #define ATRACE_TAG_DALVIK           (1<<14)
 #define ATRACE_TAG_RS               (1<<15)
 #define ATRACE_TAG_BIONIC           (1<<16)
-#define ATRACE_TAG_LAST             ATRACE_TAG_BIONIC
+#define ATRACE_TAG_POWER            (1<<17)
+#define ATRACE_TAG_LAST             ATRACE_TAG_POWER
 
 // Reserved for initialization.
 #define ATRACE_TAG_NOT_READY        (1LL<<63)