usb: add HAS_IOMEM dependency to USB_APPLEDISPLAY

warning: (USB_APPLEDISPLAY) selects BACKLIGHT_LCD_SUPPORT which has unmet direct dependencies (HAS_IOMEM)

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