net/mlx5: E-Switch, Enlarge the FDB size for the switchdev mode

The E-Switch FDB size was hard coded to 8k. Change it to be

  min(max eswitch table size, max flow counters * num flow groups)

where the max values are read from the firmware and the number of
flow groups is hard-coded as before this change.

We don't know upfront the division of flows to group. This setup allows
each group to be of size up to the where we want to support (we mandate
pairing of flows with counters for offloading). Thus, we don't expect
multiple occurences for a group which in turn adds steering hops.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Tested-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>