Kernel: Move SpinLock.h into Locking/

Author: https://github.com/boricj
Commit: 2c3b0baf76
Pull-request: https://github.com/SerenityOS/serenity/pull/8851
Reviewed-by: https://github.com/awesomekling ✅
Reviewed-by: https://github.com/bgianfo

Kernel/WorkQueue.cpp

@@ -4,9 +4,9 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <Kernel/Locking/SpinLock.h>
 #include <Kernel/Process.h>
 #include <Kernel/Sections.h>
-#include <Kernel/SpinLock.h>
 #include <Kernel/WaitQueue.h>
 #include <Kernel/WorkQueue.h>