rndis_wlan: cleanup

- remove double newlines between functions
- remove commented out function (rndis_set_config_parameter_u32())
- coding style fix in rndis_set_config_parameter_str()
- add comment banners between function sections

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>