CONFIG_ICST525 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_ICST525 (not configurable)

modulename: icst525.ko

configname: CONFIG_ICST525

Linux Kernel Configuration
└─>ICST525
In linux kernel since version 2.6.12  
source code:
arch/arm/common/icst525.c
is depended by
CONFIG_ARCH_INTEGRATOR