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

GPIO-assisted Flash Chip Support

modulename: gpio-addr-flash.ko

configname: CONFIG_MTD_GPIO_ADDR

Linux Kernel Configuration
└─>Device Drivers
└─>Memory Technology Device (MTD) support
└─>Mapping drivers for chip access
└─>GPIO-assisted Flash Chip Support
In linux kernel since version 2.6.32 (release Date: 2009-12-02)  
Map driver which allows flashes to be partially physically addressed
and assisted by GPIOs.

If compiled as a module, it will be called gpio-addr-flash.

source code:
drivers/mtd/maps//gpio-addr-flash.c