datapath: backport: openvswitch: correct encoding of set tunnel action attributes

datapath: backport: openvswitch: correct encoding of set tunnel action attributes

upstream commit:
    commit e905eabc90a5b787d8708df164543ee295bea5f2
    Author: Simon Horman <simon.horman@netronome.com>

    openvswitch: correct encoding of set tunnel action attributes

    In a set action tunnel attributes should be encoded in a
    nested action.

    I noticed this because ovs-dpctl was reporting an error
    when dumping flows due to the incorrect encoding of tunnel attributes
    in a set action.

    Fixes: fc4099f17240 ("openvswitch: Fix egress tunnel info.")
    Signed-off-by: Simon Horman <simon.horman@netronome.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Pravin B Shelar <pshelar@ovn.org>
Acked-by: Jesse Gross <jesse@kernel.org>