Add rocr namespace to core header and impl files

Change-Id: I1e1b33f9bba1078d049bc19797889988c3e43360

runtime/hsa-runtime/core/util/timer.cpp

@@ -42,6 +42,7 @@
 
 #include "core/util/timer.h"
 
+namespace rocr {
 namespace timer {
 
 accurate_clock::init::init() {
@@ -104,4 +105,5 @@ accurate_clock::init accurate_clock::accurate_clock_init;
 double fast_clock::period_ps;
 fast_clock::raw_frequency fast_clock::freq;
 fast_clock::init fast_clock::fast_clock_init;
-}
+}   //  namespace timer
+}   //  namespace rocr