net/mlx5e: Convert mlx5e_flow_steering member of mlx5e_priv to pointer

Make mlx5e_flow_steering member of mlx5e_priv a pointer.
Add dynamic allocation respectively.

Allocate fs for all profiles when initializing profile,
symmetrically deallocate at profile cleanup.

Signed-off-by: Lama Kayal <lkayal@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>