vxlan: avoid vlan processing in vxlan device.

VxLan device does not have special handling for vlan taging on egress.
Therefore it does not make sense to expose vlan offloading feature.
This patch does not change vxlan functinality.

Signed-off-by: Pravin B Shelar <pshelar@ovn.org>
Acked-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>