usb: add HAS_IOMEM dependency to USB_DWC2

drivers/built-in.o: In function `dwc2_driver_probe':
/home/vegard/linux/drivers/usb/dwc2/platform.c:491: 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/dwc2/Kconfig

 config USB_DWC2
 	tristate "DesignWare USB2 DRD Core Support"
 	depends on USB || USB_GADGET
+	depends on HAS_IOMEM
 	help
 	  Say Y here if your system has a Dual Role Hi-Speed USB
 	  controller based on the DesignWare HSOTG IP Core.