net/mlx5: Block switchdev mode while devlink traps are active

Since switchdev mode can't support  devlink traps, verify there are
no active devlink traps before moving eswitch to switchdev mode. If
there are active traps, prevent the switchdev mode configuration.

Fixes: eb3862a0 ("net/mlx5e: Enable traps according to link state")
Signed-off-by: Aya Levin <ayal@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>