Kernel: All processors use LAPIC timer when running with APIC

This makes scheduler preemption much cleaner as bsb does not have to
send smp messages to notify other processes about timer interrupt.

Also PIT percision is now "full" 0.8 us instead of 1 ms that I was using
before.

kernel/include/kernel/Scheduler.h

@@ -110,8 +110,6 @@ namespace Kernel
 
 		class ProcessorID find_least_loaded_processor() const;
 
-		void preempt();
-
 		void handle_unblock_request(const UnblockRequest&);
 		void handle_new_thread_request(const NewThreadRequest&);