PCI/ERR: Clear status of the reporting device

PCI/ERR: Clear status of the reporting device

Error handling operates on the first Downstream Port above the detected
error, but the error may have been reported by a downstream device.
Clear the AER status of the device that reported the error rather than
the first Downstream Port.

Link: https://lore.kernel.org/r/20210104230300.1277180-2-kbusch@kernel.org
Tested-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>