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

SoC Audio support for Marvell Brownstone

modulename: snd-soc-brownstone.ko

configname: CONFIG_SND_MMP_SOC_BROWNSTONE

Linux Kernel Configuration
└─>Device Drivers
└─>Sound card support
└─>Advanced Linux Sound Architecture
└─>ALSA for SoC audio support
└─>SoC Audio support for Marvell Brownstone
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Say Y if you want to add support for SoC audio on the
Marvell Brownstone reference platform.

source code:
sound/soc//pxa/