core_timing: Namespace all functions and constants in core_timing's header

All of these variables and functions are related to timings and should be within the namespace.

src/core/core_timing.h

@@ -23,6 +23,8 @@
 #include "common/common_types.h"
 #include "common/logging/log.h"
 
+namespace CoreTiming {
+
 // The below clock rate is based on Switch's clockspeed being widely known as 1.020GHz
 // The exact value used is of course unverified.
 constexpr u64 BASE_CLOCK_RATE = 1019215872; // Switch clock speed is 1020MHz un/docked
@@ -117,8 +119,6 @@ inline u64 cyclesToMs(s64 cycles) {
     return cycles * 1000 / BASE_CLOCK_RATE;
 }
 
-namespace CoreTiming {
-
 /**
  * CoreTiming begins at the boundary of timing slice -1. An initial call to Advance() is
  * required to end slice -1 and start slice 0 before the first cycle of code is executed.