default or selected kernelversion does not have config value CONFIG_SND_SOC_NUC900_AC97.
Result is shown for kernelversion 6.9.9

CONFIG_SND_SOC_NUC900_AC97 (not configurable)

modulename: snd-soc-nuc900-ac97.ko

configname: CONFIG_SND_SOC_NUC900_AC97

Linux Kernel Configuration
└─>Device Drivers
└─>Sound card support
└─>Advanced Linux Sound Architecture
└─>ALSA for SoC audio support
└─>SND_SOC_NUC900_AC97
In linux kernel since version 2.6.36 (release Date: 2010-10-20)  
source code:
sound/soc//nuc900/