net/mlx5e: Fix IPSEC stats

When IPSEC offload isn't active, the number of stats is not zero, but
the strings are not filled, leading to exposing stats with empty names.
Fix this by using the same condition for NUM_STATS and FILL_STRS.

Fixes: 0aab3e1b ("net/mlx5e: IPSec, Expose IPsec HW stat only for supporting HW")
Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Reviewed-by: Raed Salem <raeds@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>