common/sfc_efx/base: add action set spec init/fini APIs

common/sfc_efx/base: add action set spec init/fini APIs

The engine is only able to carry out chosen actions on matching packets in
a strict order. No MCDI exists to identify supported actions and the order.
Still, the definition of the latter is available from the FW documentation.

The general idea is to define an action specification structure and supply
a client driver with APIs for adding actions individually, order-dependent.
A client driver is supposed to invoke an API on every action passed by the
application, and if an out-of-order action follows, the API will reject it.

Add an action set specification stub and supply initialise / finalise APIs.

Signed-off-by: Ivan Malov <ivan.malov@oktetlabs.ru>
Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
Reviewed-by: Andy Moreton <amoreton@xilinx.com>