sunxi: Move usb-controller init code out of ehci-sunxi.c for reuse for otg

Most of the usb-controller init code found in ehci-sunxi.c also is necessary
to init the otg usb controller, so move it to a common place.

While at it also update various #ifdefs / defines for sun8i support.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>