ptp: Classify ptp over ip over vlan packets

This extends the ptp bpf to also match ptp over ip over vlan packets. The ptp
classes are changed to orthogonal bitfields representing version, transport
and vlan values to simplify matching.

Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
Signed-off-by: David S. Miller <davem@davemloft.net>