net/mlx5e: Remove dependency in IPsec initialization flows

Currently, IPsec feature is disabled because mlx5e_build_nic_netdev
is required to be called after mlx5e_ipsec_init. This requirement is
invalid as mlx5e_build_nic_netdev and mlx5e_ipsec_init initialize
independent resources.

Remove ipsec pointer check in mlx5e_build_nic_netdev so that the
two functions can be called at any order.

Fixes: 547eede0

 ("net/mlx5e: IPSec, Innova IPSec offload infrastructure")
Signed-off-by: Huy Nguyen <huyn@nvidia.com>
Reviewed-by: Raed Salem <raeds@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>