CONFIG_MACH_OPENBLOCKS_A6_DT is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_MACH_OPENBLOCKS_A6_DT.
Result is shown for kernelversion 6.2.5

Plat'Home OpenBlocks A6 (Flattened Device Tree)

modulename: board-openblocks_a6.ko

configname: CONFIG_MACH_OPENBLOCKS_A6_DT

Linux Kernel Configuration
└─>Marvell Kirkwood Implementations
└─>Plat'Home OpenBlocks A6 (Flattened Device Tree)
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Say 'Y' here if you want your kernel to support the
Plat'Home OpenBlocks A6 (Flattened Device Tree).

source code:
arch/arm/mach-kirkwood/board-openblocks_a6.c