PCI/ASPM: Update save_state when configuration changes

PCI/ASPM: Update save_state when configuration changes

Many PCIe device drivers save the configuration state of their device
during probe and restore it when their .slot_reset() hook is called during
PCIe error recovery.

If the ASPM configuration is changed after the driver's probe is called and
before an error event occurs, .slot_reset() restores the ASPM configuration
to what it was at the time of probe, not to what it was just before the
occurrence of the error event.  This leads to a mismatch in ASPM
configuration between the device and its upstream device.

Update the saved configuration of the device when the ASPM configuration
changes.

Link: https://lore.kernel.org/r/20240222174436.3565146-1-vidyas@nvidia.com
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
[bhelgaas: commit log, rebase to pci/aspm, rename to
pci_update_aspm_saved_state() since it updates only LNKCTL, update only
ASPMC and CLKREQ_EN in LNKCTL]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: David E. Box <david.e.box@linux.intel.com>