datapath: Fix wrong push/pop ethernet validation

datapath: Fix wrong push/pop ethernet validation

Upstream commit:
    commit 46ebe2834ba5b541f28ee72e556a3fed42c47570
    Author: Jaime Caamaño Ruiz <jcaamano@suse.com>
    Date:   Wed Oct 31 18:52:03 2018 +0100

    openvswitch: Fix push/pop ethernet validation

    When there are both pop and push ethernet header actions among the
    actions to be applied to a packet, an unexpected EINVAL (Invalid
    argument) error is obtained. This is due to mac_proto not being reset
    correctly when those actions are validated.

    Reported-at:
    https://mail.openvswitch.org/pipermail/ovs-discuss/2018-October/047554.html
    Fixes: 91820da6ae85 ("openvswitch: add Ethernet push and pop actions")
    Signed-off-by: Jaime Caamaño Ruiz <jcaamano@suse.com>
Tested-by: Greg Rose <gvrose8192@gmail.com>
Reviewed-by: Greg Rose <gvrose8192@gmail.com>
Reported-at: https://mail.openvswitch.org/pipermail/ovs-discuss/2018-October/047554.html
Fixes: 6fcecb85ab ("datapath: add Ethernet push and pop actions")
Signed-off-by: Jaime Caamaño Ruiz <jcaamano@suse.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>