staging: r8188eu: remove unused defines in wifi.h

None of these defines in wifi.h are used so they
can be safely removed.

Reviewed-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: Zameer Manji <zmanji@gmail.com>
Link: https://lore.kernel.org/r/20211116011451.896714-1-zmanji@gmail.com


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