staging:rtl8712: remove unused enum WIFI_STATUS_CODE

Improve readability.

Signed-off-by: Ivan Safonov <insafonov@gmail.com>
Link: https://lore.kernel.org/r/20210131080912.25264-1-insafonov@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>