net/mlx5: Rely on dev->link_active_reporting

Use dev->link_active_reporting to determine whether Data Link Layer Link
Active Reporting is available rather than re-retrieving the capability.

Link: https://lore.kernel.org/r/alpine.DEB.2.21.2305310125370.59226@angie.orcam.me.uk


Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>