Merge branch 'support-udp-encapsulation-in-packet-offload-mode'

Leon Romanovsky says:

====================
Support UDP encapsulation in packet offload mode

As was raised by Ilia in this thread [1], the ESP over UDP feature is
supported in packet offload mode. So comes this series, which adds
relevant bits to the mlx5 driver and opens XFRM core code to accept
such configuration.

NAT-T is part of IKEv2 and strongswan uses it automatically [2].

[1] https://lore.kernel.org/all/20230718092405.4124345-1-quic_ilial@quicinc.com
[2] https://wiki.strongswan.org/projects/1/wiki/NatTraversal
====================

Link: https://lore.kernel.org/r/cover.1689757619.git.leon@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>