datapath: Fix ovs_flow_key_update()

datapath: Fix ovs_flow_key_update()

Upstream commit:
    commit 6f56f6186c18e3fd54122b73da68e870687b8c59
    Author: Yi-Hung Wei <yihung.wei@gmail.com>
    Date:   Thu Mar 30 12:36:03 2017 -0700

    ovs_flow_key_update() is called when the flow key is invalid, and it is
    used to update and revalidate the flow key. Commit 329f45bc4f19
    ("openvswitch: add mac_proto field to the flow key") introduces mac_proto
    field to flow key and use it to determine whether the flow key is valid.
    However, the commit does not update the code path in ovs_flow_key_update()
    to revalidate the flow key which may cause BUG_ON() on execute_recirc().
    This patch addresses the aforementioned issue.

    Fixes: 329f45bc4f19 ("openvswitch: add mac_proto field to the flow key")
    Signed-off-by: Yi-Hung Wei <yihung.wei@gmail.com>
    Acked-by: Jiri Benc <jbenc@redhat.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Yi-Hung Wei <yihung.wei@gmail.com>
Acked-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>