Use APIC for interrupts rather than PIC.

Still rely on the PIT for now rather than the local APIC timer.

zion/common/msr.h

@@ -0,0 +1,6 @@
+#pragma once
+
+#include <stdint.h>
+
+uint64_t GetMSR(uint32_t msr);
+void SetMSR(uint32_t msr, uint64_t val);