usb: ohci-nxp: enable compile-testing

usb: ohci-nxp: enable compile-testing

The driver hardcodes a hardware I/O address the way one should
generally not do, and this prevents both compile-testing, and
moving the platform to CONFIG_ARCH_MULTIPLATFORM.

Change the code to be independent of the machine headers
to allow those two. Removing the hardcoded address would
be hard and is not necessary, so leave that in place for now.

Link: https://lore.kernel.org/r/20190809144043.476786-2-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>