usb: musb: sunxi: support module autoloading

MODULE_DEVICE_TABLE() is missing, so the module isn't auto-loading on
sunxi systems using the OTG controller. This commit adds the missing
line so it loads automatically when building it as a module and running
on a system with an USB OTG port.

Signed-off-by: Emilio López <emilio.lopez@collabora.co.uk>
Signed-off-by: Felipe Balbi <balbi@kernel.org>