staging: rtl8723au: Rename BT_WifiScanNotify() rtl8723a_BT_wifiscan_notify()

Providing a dummy wrapper also allows removing some more
CONFIG_8723AU_BT_COEXIST clutter

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