default or selected kernelversion does not have config value CONFIG_SND_AT91_SOC_ETI_B1_WM8731.
Result is shown for kernelversion 5.3.7

SoC Audio support for WM8731-based Endrelia ETI-B1 boards

modulename: snd-soc-eti-b1-wm8731.ko

configname: CONFIG_SND_AT91_SOC_ETI_B1_WM8731

Linux Kernel Configuration
└─>Device Drivers
└─>Sound card support
└─>Advanced Linux Sound Architecture
└─>ALSA for SoC audio support
└─>SoC Audio support for WM8731-based Endrelia ETI-B1 boards
In linux kernel since version 2.6.21.1 (release Date: 2007-04-27)  
Say Y if you want to add support for SoC audio on WM8731-based
Endrelia Technologies Inc ETI-B1 or ETI-C1 boards.

source code: