The patch adds support for openvswitch to configure erspan
v1 and v2. The OVS_TUNNEL_KEY_ATTR_ERSPAN_OPTS attr is added
to uapi as a binary blob to support all ERSPAN v1 and v2's
fields. Note that Previous commit "openvswitch: Add erspan tunnel
support." was reverted since it does not design properly.
Signed-off-by: William Tu <u9012063@gmail.com> Acked-by: Pravin B Shelar <pshelar@ovn.org> Signed-off-by: David S. Miller <davem@davemloft.net>