Initialize USB controllers from Usb instead of Pci

src/hulk/usb/usb.d

@@ -0,0 +1,24 @@
+/**
+ * USB (Universal Serial Bus) functionality.
+ */
+module hulk.usb.usb;
+
+import hulk.klog;
+import hulk.usb.xhci;
+import hulk.pci;
+
+struct Usb
+{
+    public static void initialize()
+    {
+        Klog.writefln("\a3Initializing USB");
+
+        foreach (pci_device; Pci.devices)
+        {
+            if (pci_device.type == Pci.XHCI_CONTROLLER)
+            {
+                XHCI.build(&pci_device);
+            }
+        }
+    }
+}