ar5523: use module_usb_driver to simplify the code

Use the module_usb_driver() macro to make the code simpler
by eliminating module_init and module_exit calls.

dpatch engine is used to auto generate this patch.
(https://github.com/weiyj/dpatch

)

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: John W. Linville <linville@tuxdriver.com>