ethdev: deprecate direction attributes in transfer flows

ethdev: deprecate direction attributes in transfer flows

Attributes "ingress" and "egress" can only apply unambiguosly
to non-"transfer" flows. In "transfer" flows, the standpoint
is effectively shifted to the embedded switch. There can be
many different endpoints connected to the switch, so the
use of "ingress" / "egress" does not shed light on which
endpoints precisely can be considered as traffic sources.

Add relevant deprecation notices and suggest the use of precise
traffic source items (PORT_REPRESENTOR and REPRESENTED_PORT).

Signed-off-by: Ivan Malov <ivan.malov@oktetlabs.ru>
Acked-by: Ori Kam <orika@nvidia.com>
Acked-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>