net/mlx5: Not returning mlx5_link_info table when speed is unknown

Because mlx5e_link_info and mlx5e_ext_link_info have holes
e.g. Azure mlx5 reports PTYS 19. Do not return it unless speed
is retrieved successfully.

Fixes: 65a5d355 ("net/mlx5: Refactor link speed handling with mlx5_link_info struct")
Suggested-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Li Tian <litian@redhat.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/20250910003732.5973-1-litian@redhat.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>