net/mlx5: Check FW limitations on log_max_qp before setting it

When setting HCA capabilities, set log_max_qp to be the minimum
between the selected profile's value and the HCA limitation.

Fixes: 938fe83c ('net/mlx5_core: New device capabilities...')
Signed-off-by: Noa Osherovich <noaos@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>