usb: hcd-xhci-sysbus: Attach xhci to sysbus device

Use XHCI as sysbus device, add memory region property to get the
address space instance for dma read/write.

Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
Message-id: 1600957256-6494-5-git-send-email-sai.pavan.boddu@xilinx.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff --git a/hw/usb/Kconfig b/hw/usb/Kconfig
index bab582f..4dd2ba9 100644
--- a/hw/usb/Kconfig
+++ b/hw/usb/Kconfig
@@ -48,6 +48,11 @@
     depends on PCI
     select USB_XHCI
 
+config USB_XHCI_SYSBUS
+    bool
+    default y if USB_XHCI
+    select USB
+
 config USB_MUSB
     bool
     select USB