net/mlx5: Fix query ISSI flow

In old FWs query ISSI command is not supported and for some of those FWs
it might fail with status other than "MLX5_CMD_STAT_BAD_OP_ERR".

In such case instead of failing the driver load, we will treat any FW
status other than 0 for Query ISSI FW command as ISSI not supported and
assume ISSI=0 (most basic driver/FW interface).

In case of driver syndrom (query ISSI failure by driver) we will fail
driver load.

Fixes: f62b8bb8

 ('net/mlx5: Extend mlx5_core to support ConnectX-4
Ethernet functionality')
Signed-off-by: Kamal Heib <kamalh@mellanox.com>

Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>