PCI/ASPM: Enable only L0s and L1 for devicetree platforms

PCI/ASPM: Enable only L0s and L1 for devicetree platforms

f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM states for devicetree
platforms") enabled Clock Power Management and L1 PM Substates, but those
features depend on CLKREQ# and possibly other device-specific
configuration.  We don't know whether CLKREQ# is supported, so we shouldn't
blindly enable Clock PM and L1 PM Substates.

Enable only ASPM L0s and L1, and only when both ends of the link advertise
support for them.

Fixes: f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM states for devicetree platforms")
Reported-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Link: https://lore.kernel.org/r/db5c95a1-cf3e-46f9-8045-a1b04908051a@xenosoft.de/
Reported-by: FUKAUMI Naoki <naoki@radxa.com>
Closes: https://lore.kernel.org/r/22594781424C5C98+22cb5d61-19b1-4353-9818-3bb2b311da0b@radxa.com/
Reported-by: Herve Codina <herve.codina@bootlin.com>
Link: https://lore.kernel.org/r/20251015101304.3ec03e6b@bootlin.com/
Reported-by: Diederik de Haas <diederik@cknow-tech.com>
Closes: https://lore.kernel.org/r/DDJXHRIRGTW9.GYC2ULZ5WQAL@cknow-tech.com/
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: FUKAUMI Naoki <naoki@radxa.com>
Tested-by: Diederik de Haas <diederik@cknow-tech.com>
Acked-by: Dragan Simic <dsimic@manjaro.org>
Link: https://patch.msgid.link/20251023180645.1304701-1-helgaas@kernel.org