Currently the bridge FORWARD/POST_ROUTING chains treats all
non-IPv4 packets as IPv6.  This packet fixes that by returning
NF_ACCEPT on non-IP packets instead, just as is done in PRE_ROUTING.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>