ACPI/PCI: PCIe AER _OSC support capabilities called when root bridge added

The _OSC capability OSC_EXT_PCI_CONFIG_SUPPORT is set when the root
bridge is added with pci_acpi_osc_support(), so we no longer need to do
it in the PCIe AER driver.

Signed-off-by: Andrew Patterson <andrew.patterson@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>