PCI/AER: Add additional PCIe AER error strings

Add strings for all AER error bits defined in PCIe r3.0.

[bhelgaas: changelog, drop designated initializer change]
Signed-off-by: Chen, Gong <gong.chen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>