default or selected kernelversion does not have config value CONFIG_DRM_DUMB_VGA_DAC.
Result is shown for kernelversion 6.8.2

Dumb VGA DAC Bridge support

modulename: dumb-vga-dac.ko

configname: CONFIG_DRM_DUMB_VGA_DAC

Linux Kernel Configuration
└─>Device Drivers
└─>Graphics support
└─>Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)
└─>Display Interface Bridges
└─>Device Tree and Open Firmware support
└─>Dumb VGA DAC Bridge support
In linux kernel since version 4.1 (release Date: 2015-06-21)  
Support for non-programmable RGB to VGA DAC bridges, such as ADI
ADV7123, TI THS8134 and THS8135 or passive resistor ladder DACs.

source code: