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

Xilinx PCI host bridge support

modulename: xilinx_pci.ko

configname: CONFIG_XILINX_PCI

Linux Kernel Configuration
└─>Platform support
└─>Xilinx PCI host bridge support
In linux kernel since version 2.6.31 (release Date: 2009-09-09)  
source code:
arch/powerpc/sysdev/xilinx_pci.c

is depended by
CONFIG_XILINX_ML510