net/mlx5e: Change the warning when ignore_flow_level is not supported

Downgrade the print from mlx5_core_warn() to mlx5_core_dbg(), as it
is just a statement of fact that firmware doesn't support ignore flow
level.

And change the wording to "firmware flow level support is missing", to
make it more accurate.

Fixes: ae2ee3be

 ("net/mlx5: CT: Remove warning of ignore_flow_level support for VFs")
Signed-off-by: Jianbo Liu <jianbol@nvidia.com>
Suggested-by: Elliott, Robert (Servers) <elliott@hpe.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>