Kernel: Fix timer early wake message

When printing early return message, current time was read twice. This
could lead to early return check failing, but when printing and reading
the time again subtraction overflow would happen.

kernel/kernel/Timer/Timer.cpp

@@ -75,8 +75,9 @@ namespace Kernel
 			return;
 		uint64_t wake_time = ms_since_boot() + ms;
 		Scheduler::get().set_current_thread_sleeping(wake_time);
-		if (ms_since_boot() < wake_time)
-			dwarnln("sleep woke {} ms too soon", wake_time - ms_since_boot());
+		uint64_t current_time = ms_since_boot();
+		if (current_time < wake_time)
+			dwarnln("sleep woke {} ms too soon", wake_time - current_time);
 	}
 
 	timespec SystemTimer::real_time() const