CONFIG_ARCH_ATLAS7 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CSR SiRFSoC ATLAS7 ARM Cortex A7 Platform

configname: CONFIG_ARCH_ATLAS7

Linux Kernel Configuration
└─>CSR SiRF
└─>CSR SiRFSoC ATLAS7 ARM Cortex A7 Platform
In linux kernel since version 3.10 (release Date: 2013-06-30)  
Support for CSR SiRFSoC ARM Cortex A7 Platform