[INTERRUPTS] Enabling the APIC timer

kernel/include/apic.h

@@ -4,6 +4,8 @@
 void apic_init();
 void apic_interrupt(uint8_t destination, uint8_t level, uint8_t type, uint8_t vector);
 void apic_ack();
+void apic_timer(uint64_t us);
+void apic_timer_stop();
 #define APIC_INT_LEVEL_ASSERT 0x1
 #define APIC_INT_LEVEL_DEASSERT 0x0
 #define APIC_INT_TYPE_FIXED 0x0