default or selected kernelversion does not have config value CONFIG_MTD_CONCAT.
Result is shown for kernelversion 5.4.69
MTD concatenating support
modulename: mtdconcat.ko
configname: CONFIG_MTD_CONCAT
Linux Kernel Configuration
└─>Device Drivers
└─>Memory Technology Device (MTD) support
└─>MTD concatenating support
In linux kernel since version 2.6.12
Support for concatenating several MTD devices into a single
(virtual) one. This allows you to have -for example- a JFFS(2)
file system spanning multiple physical flash chips. If unsure,
say 'Y'.
(virtual) one. This allows you to have -for example- a JFFS(2)
file system spanning multiple physical flash chips. If unsure,
say 'Y'.