CONFIG_MPC5121_GENERIC is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc
default or selected kernelversion does not have config value CONFIG_MPC5121_GENERIC.
Result is shown for kernelversion 6.2.5

Generic support for simple MPC5121 based boards

modulename: mpc5121_generic.ko

configname: CONFIG_MPC5121_GENERIC

Linux Kernel Configuration
└─>Generic support for simple MPC5121 based boards
In linux kernel since version 2.6.27 (release Date: 2008-10-09)  
This option enables support for simple MPC5121 based boards
which do not need custom platform specific setup.

Compatible boards include: Protonic LVT base boards (ZANMCU
and VICVT2).

source code: