kernel/handle_table: Move private static functions into the cpp file

These don't depend on class state, and are effectively implementation
details, so they can go into the cpp file .

src/core/hle/kernel/handle_table.cpp

@@ -12,6 +12,15 @@
 #include "core/hle/kernel/thread.h"
 
 namespace Kernel {
+namespace {
+constexpr u16 GetSlot(Handle handle) {
+    return handle >> 15;
+}
+
+constexpr u16 GetGeneration(Handle handle) {
+    return handle & 0x7FFF;
+}
+} // Anonymous namespace
 
 HandleTable::HandleTable() {
     next_generation = 1;