bridging: fix rx_handlers return code

The frames for which rx_handlers return RX_HANDLER_CONSUMED are no longer
counted as dropped. They are counted as successfully received by
'netif_receive_skb'.

This allows network interface drivers to correctly update their RX-OK and
RX-DRP counters based on the result of 'netif_receive_skb'.

Signed-off-by: Cristian Bercaru <B43982@freescale.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>