net/sfc: insert switchdev mode MAE rules

net/sfc: insert switchdev mode MAE rules

By default, the firmware is in EVB mode, but insertion of the first MAE
rule resets it to switchdev mode automatically and removes all automatic
MAE rules added by EVB support. On initialisation, insert MAE rules that
forward traffic between PHY and PF.

Add an API for creation and insertion of driver-internal MAE
rules(flows).

Signed-off-by: Igor Romanov <igor.romanov@oktetlabs.ru>
Signed-off-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Reviewed-by: Andy Moreton <amoreton@xilinx.com>
Reviewed-by: Ivan Malov <ivan.malov@oktetlabs.ru>