Initialize USB controllers from Usb instead of Pci

src/hulk/hulk.d

@@ -22,6 +22,7 @@ import hulk.acpi;
 import hulk.apic;
 import hulk.rtc;
 import hulk.serial;
+import hulk.usb;
 
 extern extern(C) __gshared ubyte _hulk_bss_size;
 
@@ -82,6 +83,7 @@ void hulk_start()
             t.year, t.month, t.day, t.hour, t.minute, t.second);
 
     Pci.initialize();
+    Usb.initialize();
     sti();
 
     for (;;)