PCI: Restore PCI expansion ROM P2P prefetch window creation

Restore PCI expansion ROM P2P prefetch window creation.

This patch reverts previous "Avoid creating P2P prefetch
window for expansion ROMs" change due to regressions that
were spotted on some systems.

Signed-off-by: Gary Hade <garyhade@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>