Kernel: Use a const reference to RegisterState in IRQ handling

Author: https://github.com/supercomputer7
Commit: e880fe0765
Pull-request: https://github.com/SerenityOS/serenity/pull/1396
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/shannonbooth ✅

Kernel/Scheduler.cpp

@@ -580,7 +580,7 @@ void Scheduler::initialize()
     load_task_register(s_redirection.selector);
 }
 
-void Scheduler::timer_tick(RegisterState& regs)
+void Scheduler::timer_tick(const RegisterState& regs)
 {
     if (!Thread::current)
         return;