usb: add HAS_IOMEM dependency to USB_XHCI_HCD

drivers/built-in.o: In function `xhci_plat_probe':
/home/vegard/linux/drivers/usb/host/xhci-plat.c:160: undefined reference to `devm_ioremap_resource'
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/Kconfig

@@ -18,6 +18,7 @@ config USB_C67X00_HCD
 
 config USB_XHCI_HCD
 	tristate "xHCI HCD (USB 3.0) support"
+	depends on HAS_IOMEM
 	---help---
 	  The eXtensible Host Controller Interface (xHCI) is standard for USB 3.0
 	  "SuperSpeed" host controller hardware.