PCI/AER: Reset link for devices below Root Port or Downstream Port

When a PCIe device reports a fatal error, we reset the link leading
to it.  Previously we only did this for devices below Downstream Ports,
not for devices directly below Root Ports.

This patch changes that so we reset the link leading to devices below
Root Ports just like we do for those below Downstream Ports.

[bhelgaas: changelog, keep dev_printk(KERN_DEBUG)]
Signed-off-by: Betty Dall <betty.dall@hp.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>