general: Use deducation guides for std::lock_guard and std::unique_lock

Since C++17, the introduction of deduction guides for locking facilities
means that we no longer need to hardcode the mutex type into the locks
themselves, making it easier to switch mutex types, should it ever be
necessary in the future.

src/core/hle/kernel/kernel.cpp

@@ -34,7 +34,7 @@ static void ThreadWakeupCallback(u64 thread_handle, [[maybe_unused]] s64 cycles_
     const auto& system = Core::System::GetInstance();
 
     // Lock the global kernel mutex when we enter the kernel HLE.
-    std::lock_guard<std::recursive_mutex> lock(HLE::g_hle_lock);
+    std::lock_guard lock{HLE::g_hle_lock};
 
     SharedPtr<Thread> thread =
         system.Kernel().RetrieveThreadFromWakeupCallbackHandleTable(proper_handle);