net/mlx5e: Set FEC to auto when configured mode is not supported

When configuring FEC mode, driver tries to set it for all available
link types. If a link type doesn't support a FEC mode, set this link
type to auto (FW best effort). Prior to this patch, when a link type
didn't support a FEC mode is was set to no FEC.

Signed-off-by: Aya Levin <ayal@mellanox.com>
Reviewed-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>