usb: add HAS_IOMEM dependency to USB_SL811_HCD

  CC      drivers/usb/host/xhci-mtk.o
drivers/usb/host/xhci-mtk.c:135:12: warning: ‘xhci_mtk_host_disable’ defined but not used [-Wunused-function]
 static int xhci_mtk_host_disable(struct xhci_hcd_mtk *mtk)
            ^
drivers/usb/host/xhci-mtk.c:313:13: warning: ‘usb_wakeup_enable’ defined but not used [-Wunused-function]
 static void usb_wakeup_enable(struct xhci_hcd_mtk *mtk)
             ^
drivers/usb/host/xhci-mtk.c:321:13: warning: ‘usb_wakeup_disable’ defined but not used [-Wunused-function]
 static void usb_wakeup_disable(struct xhci_hcd_mtk *mtk)
             ^
  CC      drivers/usb/host/sl811-hcd.o
drivers/usb/host/sl811-hcd.c: In function ‘sl811h_remove’:
drivers/usb/host/sl811-hcd.c:1607:3: error: implicit declaration of function ‘iounmap’ [-Werror=implicit-function-declaration]
   iounmap(sl811->data_reg);
   ^
drivers/usb/host/sl811-hcd.c: In function ‘sl811h_probe’:
drivers/usb/host/sl811-hcd.c:1669:3: error: implicit declaration of function ‘ioremap’ [-Werror=implicit-function-declaration]
   addr_reg = ioremap(addr->start, 1);
   ^
drivers/usb/host/sl811-hcd.c:1669:12: warning: assignment makes pointer from integer without a cast [enabled by default]
   addr_reg = ioremap(addr->start, 1);
            ^
drivers/usb/host/sl811-hcd.c:1675:12: warning: assignment makes pointer from integer without a cast [enabled by default]
   data_reg = ioremap(data->start, 1);
            ^

Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>