PCI/ACPI: Correct error message for ASPM disabling

If _OSC execution fails today for platforms without an _OSC entry, code is
printing a misleading message saying disabling ASPM as follows:

  acpi PNP0A03:00: _OSC failed (AE_NOT_FOUND); disabling ASPM

We need to ensure that platform supports ASPM to begin with.
Reported-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Sinan Kaya <okaya@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/acpi/pci_root.c

@@ -455,8 +455,9 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm)
 	decode_osc_support(root, "OS supports", support);
 	status = acpi_pci_osc_support(root, support);
 	if (ACPI_FAILURE(status)) {
-		dev_info(&device->dev, "_OSC failed (%s); disabling ASPM\n",
-			 acpi_format_exception(status));
+		dev_info(&device->dev, "_OSC failed (%s)%s\n",
+			 acpi_format_exception(status),
+			 pcie_aspm_support_enabled() ? "; disabling ASPM" : "");
 		*no_aspm = 1;
 		return;
 	}