staging:wlan-ng: clean some more functions

the function p80211netdev_rx doesnt' need a return at the end
and also remove some new lines

the function p80211knetdev_set_mac_address doesn't need the result
variable assigned as it gets a return from p80211req_dorequest function

Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>