common/sfc_efx/base: add match spec validate API

common/sfc_efx/base: add match spec validate API

MAE has restrictions on what kind of mask a particular field can have in
a match specification. Add an API for client drivers to check
specifications.

The patch defines a field description list, whilst the list itself is
left empty. This is to provide a general idea of how field properties
will be used to validate a match specification. Particular fields
will be added to the list by follow-up patches.

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