Build: Fixed some warnings

src/core/hle/kernel/kernel.cpp

@@ -96,7 +96,7 @@ ResultCode HandleTable::Close(Handle handle) {
     if (!IsValid(handle))
         return ERR_INVALID_HANDLE;
 
-    size_t slot = GetSlot(handle);
+    u16 slot = GetSlot(handle);
 
     objects[slot] = nullptr;
 
@@ -127,7 +127,7 @@ SharedPtr<Object> HandleTable::GetGeneric(Handle handle) const {
 }
 
 void HandleTable::Clear() {
-    for (size_t i = 0; i < MAX_COUNT; ++i) {
+    for (u16 i = 0; i < MAX_COUNT; ++i) {
         generations[i] = i + 1;
         objects[i] = nullptr;
     }

src/core/hle/kernel/kernel.h

@@ -253,7 +253,7 @@ private:
      */
     static const size_t MAX_COUNT = 4096;
 
-    static size_t GetSlot(Handle handle)    { return handle >> 15; }
+    static u16 GetSlot(Handle handle)    { return handle >> 15; }
     static u16 GetGeneration(Handle handle) { return handle & 0x7FFF; }
 
     /// Stores the Object referenced by the handle or null if the slot is empty.

src/core/hle/kernel/timer.cpp

@@ -63,7 +63,7 @@ void Timer::Clear() {
 
 /// The timer callback event, called when a timer is fired
 static void TimerCallback(u64 timer_handle, int cycles_late) {
-    SharedPtr<Timer> timer = timer_callback_handle_table.Get<Timer>(timer_handle);
+    SharedPtr<Timer> timer = timer_callback_handle_table.Get<Timer>(static_cast<Handle>(timer_handle));
 
     if (timer == nullptr) {
         LOG_CRITICAL(Kernel, "Callback fired for invalid timer %08X", timer_handle);