CONFIG_PPC4xx_PCI_EXPRESS is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

CONFIG_PPC4xx_PCI_EXPRESS (not configurable)

configname: CONFIG_PPC4xx_PCI_EXPRESS

Linux Kernel Configuration
└─>PPC4xx_PCI_EXPRESS
In linux kernel since version 2.6.25 (release Date: 2008-04-16)  

is depended by
CONFIG_AKEBONO