MPC85xx: TQM85xx: make standard PCI/PCI-X configurable

The TQM8548_AG module does not have the standard PCI/PCI-X interface
connected but just the PCI Express interface . So far it was not
possible to disable it without disabling the complete PCI interface
(CONFIG_PCI) including PCI Express.

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>