rndis_wlan: cleanup, rename and reorder enums and structures

Rename enums and structures to ndis_80211_* for greater readability.
Also change order so that enumerations are presented first.

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