net/mlx5e: remove IEEE/CEE mode check when setting DCBX mode

Currently, the function setdcbx fails if the request dcbx mode
is either IEEE or CEE. We remove the IEEE/CEE mode check because
we support both IEEE and CEE interfaces.

Fixes: 3a6a931d

 ("net/mlx5e: Support DCBX CEE API")
Signed-off-by: Huy Nguyen <huyn@mellanox.com>
Reviewed-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>