CONFIG_ARCH_CNS3XXX is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Cavium Networks CNS3XXX family

modulename: cns3xxx.ko

and/or

core.ko

configname: CONFIG_ARCH_CNS3XXX

ARM system type
└─>Cavium Networks CNS3XXX family
In linux kernel since version 2.6.35 (release Date: 2010-08-01)  
Support for Cavium Networks CNS3XXX platform.

source code:
/arch/arm/mach-cns3xxx/

depends
 or CONFIG_ARCH_MULTI_V6