PCI/ERR: Recover from RCEC AER errors

[ Upstream commit a175102b ]

A Root Complex Event Collector (RCEC) collects and signals AER errors that
were detected by Root Complex Integrated Endpoints (RCiEPs), but it may
also signal errors it detects itself.  This is analogous to errors detected
and signaled by a Root Port.

Update the AER service driver to claim RCECs in addition to Root Ports.
Add support for handling RCEC-detected AER errors.  This does not
include handling RCiEP-detected errors that are signaled by the RCEC.

Note that we expect these errors only from the native AER and APEI paths,
not from DPC or EDR.

[bhelgaas: split from combined RCEC/RCiEP patch, commit log]
Signed-off-by: Sean V Kelley <sean.v.kelley@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>