staging: rt8192u: remove #ifdef RTL8192U in r8192U.h

This patch removes #ifdef RTL8192U header guard and the code that falls
outside it, since RTL8192U is defined.

Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>