PCI/ERR: Retain status from error notification

PCI/ERR: Retain status from error notification

Overwriting the frozen detected status with the result of the link reset
loses the NEED_RESET result that drivers are depending on for error
handling to report the .slot_reset() callback. Retain this status so
that subsequent error handling has the correct flow.

Link: https://lore.kernel.org/r/20210104230300.1277180-4-kbusch@kernel.org
Reported-by: Hinko Kocevar <hinko.kocevar@ess.eu>
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>