net/mlx5: E-Switch, Increase number of FTEs in FDB in switchdev mode

The max FTE number should be the max number of SQs that can be opened.
Ethernet representors open one SQ each. Once we add IB representor this
will increase (depends on the user). For now lets start with 31
per IB representor and if needed increase in the future.

This increase only affects the number of FTEs in the slow path FDB,
offloaded rules (done via TC on the fast path portion of the FDB)
aren't affected.

Signed-off-by: Mark Bloch <markb@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>