PCI/PTM: Remove error message at boot

PCI/PTM: Remove error message at boot

Since 39850ed51062 ("PCI/PTM: Save/restore Precision Time Measurement
Capability for suspend/resume"), devices that have PTM capability but
don't enable it see this message on calls to pci_save_state():

  no suspend buffer for PTM

Drop the message, it's perfectly fine not to use a capability.

Fixes: 39850ed51062 ("PCI/PTM: Save/restore Precision Time Measurement Capability for suspend/resume")
Link: https://lore.kernel.org/r/20210811185955.3112534-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: David E. Box <david.e.box@linux.intel.com>