net/mlx5: Remove redundant vport_group_manager cap check

It's enough to check for esw_manager cap for get the esw flow table
caps.

Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Maor Dickman <maord@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>