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

CONFIG_MXS_HAVE_PLATFORM_FEC (not configurable)

modulename: platform-fec.ko

configname: CONFIG_MXS_HAVE_PLATFORM_FEC

Linux Kernel Configuration
└─>MXS_HAVE_PLATFORM_FEC
In linux kernel since version 2.6.38 (release Date: 2011-03-14)  
source code:
arch/arm/mach-mxs/devices/platform-fec.c
is selected by
CONFIG_FEC