net/sfc: assign correct m-ports to independent switch ports

net/sfc: assign correct m-ports to independent switch ports

In accordance with patches [1-4], MAE admin ethdev represents a
network port and not the PF which it sits on. Rework the way
how "ethdev" and "entity" m-ports are assigned in SW switch
port entries of independent ethdevs. Explain in comments.

[1] commit 081e42dab11d ("ethdev: add port representor item to flow API")
[2] commit 49863ae2bf95 ("ethdev: add represented port item to flow API")
[3] commit 8edb6bc0263e ("ethdev: add port representor action to flow API")
[4] commit 88caad251c8d ("ethdev: add represented port action to flow API")

Signed-off-by: Ivan Malov <ivan.malov@oktetlabs.ru>
Reviewed-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>