default or selected kernelversion does not have config value CONFIG_SND_SOC_SMDK_SPDIF.
Result is shown for kernelversion 5.4.69
SoC S/PDIF Audio support for SMDK
modulename: snd-soc-smdk-spdif.ko
configname: CONFIG_SND_SOC_SMDK_SPDIF
Linux Kernel Configuration
└─>Device Drivers
└─>Sound card support
└─>Advanced Linux Sound Architecture
└─>ALSA for SoC audio support
└─>SoC S/PDIF Audio support for SMDK
In linux kernel since version 2.6.37 (release Date: 2011-01-04)
Say Y if you want to add support for SoC S/PDIF audio on the SMDK.