staging: r8188eu: remove unused _RND* from osdep_service.h

Remove the unused macro _RND() and the unused functions _RND256(),
_RND512() from osdep_service.h.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20220407125742.7814-6-straube.linux@gmail.com


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