PCI/AER: Clear AER status from Root Port when resetting Downstream Port

The pci_dev parameter given to aer_root_reset() may be a Downstream Port
rather than the Root Port. Get the Root Port from the provided device in
order to clear the root's AER status.

Link: https://lore.kernel.org/r/20210104230300.1277180-3-kbusch@kernel.orgTested-by: Hedi Berriche <hedi.berriche@hpe.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Sean V Kelley <sean.v.kelley@intel.com>
Acked-by: Hedi Berriche <hedi.berriche@hpe.com>

drivers/pci/pcie/aer.c

@@ -1388,7 +1388,7 @@ static pci_ers_result_t aer_root_reset(struct pci_dev *dev)
 	if (type == PCI_EXP_TYPE_RC_END)
 		root = dev->rcec;
 	else
-		root = dev;
+		root = pcie_find_root_port(dev);
 
 	/*
 	 * If the platform retained control of AER, an RCiEP may not have