Revert "openvswitch: Add erspan tunnel support."

This reverts commit ceaa001a.

The OVS_TUNNEL_KEY_ATTR_ERSPAN_OPTS attr should be designed
as a nested attribute to support all ERSPAN v1 and v2's fields.
The current attr is a be32 supporting only one field.  Thus, this
patch reverts it and later patch will redo it using nested attr.

Signed-off-by: William Tu <u9012063@gmail.com>
Cc: Jiri Benc <jbenc@redhat.com>
Cc: Pravin Shelar <pshelar@ovn.org>
Acked-by: Jiri Benc <jbenc@redhat.com>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>