This patch changes the prototpye of the ip6_mr_forward() method to return void
instead of int.

The ip6_mr_forward() method always returns 0; moreover, the return value of this
method is not checked anywhere.
Signed-off-by: NRami Rosen <ramirose@gmail.com>
Acked-by: NNicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>