usb: dwc3: Make sparse a bit happier

usb: dwc3: Make sparse a bit happier

Fixes the following warnings:
drivers/usb/dwc3/io.h:43:31: warning: incorrect type in argument 1 (different address spaces)
drivers/usb/dwc3/io.h:43:31:    expected void *base
drivers/usb/dwc3/io.h:43:31:    got void [noderef] <asn:2>*
drivers/usb/dwc3/io.h:62:32: warning: incorrect type in argument 1 (different address spaces)
drivers/usb/dwc3/io.h:62:32:    expected void *base
drivers/usb/dwc3/io.h:62:32:    got void [noderef] <asn:2>*

This fixes the noisiest ones as they get emitted multiple times.
A few warnings remain, for which the proper fix is less clear.

No behaviour change is expected.

Signed-off-by: Vincent Pelletier <plr.vincent@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>