default or selected kernelversion does not have config value CONFIG_SND_AU1X00.
Result is shown for kernelversion 6.5.1

Au1x00 AC97 Port Driver (DEPRECATED)

modulename: snd-au1x00.ko

configname: CONFIG_SND_AU1X00

Linux Kernel Configuration
└─>Device Drivers
└─>Sound card support
└─>Advanced Linux Sound Architecture
└─>MIPS sound devices
└─>Au1x00 AC97 Port Driver (DEPRECATED)
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
ALSA Sound driver for the Au1x00's AC97 port.

Newer drivers for ASoC are available, please do not use
this driver as it will be removed in the future.

source code:
sound/mips//