Staging: batman-adv: remove redundant is_my_mac() check in route_unicast_packet

Callers should check the if the received packet is for us before it
calls route_unicast_packet.

Signed-off-by: Andreas Langer <an.langer@gmx.de>
Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>