Enable PIT ISR to count milliseconds

src/hulk/hulk.d

@@ -23,6 +23,7 @@ import hulk.apic;
 import hulk.rtc;
 import hulk.serial;
 import hulk.usb;
+import hulk.pit;
 
 extern extern(C) __gshared ubyte _hulk_bss_size;
 
@@ -81,7 +82,7 @@ void hulk_start()
     Rtc.time t = Rtc.read_rtc_time();
     Klog.writefln("System time is 20%02u-%02u-%02u %02u:%02u:%02u",
             t.year, t.month, t.day, t.hour, t.minute, t.second);
-
+    Pit.initialize();
     Pci.initialize();
     Usb.initialize();
     sti();