usb: dwc2: fix "iomem 0x00000000" message

Set the iomem parameters in the usb_hcd to fix this misleading
message during driver load:
dwc2 c9100000.usb: irq 22, io mem 0x00000000

Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>