CONFIG_ARCH_VEXPRESS_CA9X4 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Versatile Express Cortex-A9x4 tile

modulename: ct-ca9x4.ko

configname: CONFIG_ARCH_VEXPRESS_CA9X4

Linux Kernel Configuration
└─>Versatile Express platform type
└─>Versatile Express Cortex-A9x4 tile
In linux kernel since version 2.6.35 (release Date: 2010-08-01)  
source code:
arch/arm/mach-vexpress/ct-ca9x4.c