A Root Complex Event Collector terminates error and PME messages from
associated RCiEPs.

Use the RCEC Endpoint Association Extended Capability to identify
associated RCiEPs. Link the associated RCiEPs as the RCECs are enumerated.
Co-developed-by: NQiuxu Zhuo <qiuxu.zhuo@intel.com>
Link: https://lore.kernel.org/r/20201121001036.8560-12-sean.v.kelley@intel.com
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> # non-native/no RCEC
Signed-off-by: NQiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: NSean V Kelley <sean.v.kelley@intel.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>