staging: rtl8723au: Remove a pile of fluff for calling into a bunch of no-op functions

The whole antenna diversity selection was completely pointless as all
the end functions called were no-ops.

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>