PCI/ACPI: Don't reset a fwnode set by OF

Commit 375553a9 ("PCI: Setup ACPI fwnode early and at the same time
with OF") added a call to pci_set_acpi_fwnode() in pci_setup_device(),
which unconditionally clears any fwnode previously set by
pci_set_of_node().

pci_set_acpi_fwnode() looks for ACPI_COMPANION(), which only returns the
existing fwnode if it was set by ACPI_COMPANION_SET(). If it was set by
OF instead, ACPI_COMPANION() returns NULL and pci_set_acpi_fwnode()
accidentally clears the fwnode. To fix this, look for any fwnode instead
of just ACPI companions.

Fixes a virtio-iommu boot regression in v5.15-rc1.

Fixes: 375553a9 ("PCI: Setup ACPI fwnode early and at the same time with OF")
Link: https://lore.kernel.org/r/20210913172358.1775381-1-jean-philippe@linaro.orgSigned-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/pci/pci-acpi.c

@@ -937,7 +937,7 @@ static struct acpi_device *acpi_pci_find_companion(struct device *dev);
 
 void pci_set_acpi_fwnode(struct pci_dev *dev)
 {
-	if (!ACPI_COMPANION(&dev->dev) && !pci_dev_is_added(dev))
+	if (!dev_fwnode(&dev->dev) && !pci_dev_is_added(dev))
 		ACPI_COMPANION_SET(&dev->dev,
 				   acpi_pci_find_companion(&dev->dev));
 }