PCI/AER: Specify the type of Port that was reset

The AER driver may be called upon to reset either a Downstream or a Root
Port. Check which type it is to properly identify it when logging that
the reset occurred.

Link: https://lore.kernel.org/r/20210104230300.1277180-5-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: Hedi Berriche <hedi.berriche@hpe.com>