PCI: pci-bridge-emul: Use new constant PCI_STATUS_ERROR_BITS

Use new constant PCI_STATUS_ERROR_BITS to simplify the code.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>