PCI/AER: Clear device status bits during ERR_FATAL and ERR_NONFATAL

Clear the device status bits while handling both ERR_FATAL and ERR_NONFATAL
cases.

Signed-off-by: Oza Pawandeep <poza@codeaurora.org>
[bhelgaas: rename to pci_aer_clear_device_status(), declare internal to PCI
core instead of exposing it everywhere]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>