CONFIG_NIOS2_ARCH_REVISION is not available for thedefaultarchitecture x86.
Result is shown for architecture nios2

Select Nios II architecture revision

configname: CONFIG_NIOS2_ARCH_REVISION

Linux Kernel Configuration
└─>Platform options
└─>Select Nios II architecture revision
In linux kernel since version 4.2 (release Date: 2015-08-30)  
Select between Nios II R1 and Nios II R2 . The architectures
are binary incompatible. Default is R1 .