net: ppp: resolve forwarding path for bridge pppoe devices

Pass on the PPPoE session ID, destination hardware address and the real
device.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>