staging: rtl8712: use common ieee80211 constants

Many defined constants in wifi.h are unused and/or available from
<linux/ieee80211.h>, some with slightly different names. Use the
common ones, rename where necessary and remove unused.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20200701164213.4205-1-straube.linux@gmail.com


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