default or selected kernelversion does not have config value CONFIG_SND_SOC_AMD_LEGACY_SDW_MACH.
Result is shown for kernelversion 6.6.75

AMD Legacy(No DSP) Soundwire Machine Driver Support

modulename: snd-acp-sdw-legacy-mach.ko

configname: CONFIG_SND_SOC_AMD_LEGACY_SDW_MACH

Linux Kernel Configuration
└─>Device Drivers
└─>Sound card support
└─>Advanced Linux Sound Architecture
└─>ALSA for SoC audio support
└─>PCI support
└─>AMD Legacy(No DSP) Soundwire Machine Driver Support
In linux kernel since version 6.13 (release Date: 2025-01-19)  
This option enables Legacy(No DSP) sound card support for SoundWire
enabled AMD platforms along with ACP PDM controller.
Say Y if you want to enable SoundWire based machine driver support
on AMD platform.
If unsure select "N".

source code:
sound/soc//amd/acp/