staging: w35und: Inline mlme_s.h to core.h

The mlme_s.h header is included in one place. As the header is very small, just
inline it to core.h.

Cc: Lars Lindley <lindley@coyote.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Ruslan Pisarev <ruslan@rpisarev.org.ua>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>