CONFIG_NIOS2_CI_SWAB_NO is not available for thedefaultarchitecture x86.
Result is shown for architecture nios2

Byteswap custom instruction number

configname: CONFIG_NIOS2_CI_SWAB_NO

Linux Kernel Configuration
└─>Platform options
└─>Byteswap custom instruction number
In linux kernel since version 3.19 (release Date: 2015-02-08)  
Number of the instruction as configured in QSYS Builder.