CONFIG_ENVCTRL is not available for thedefaultarchitecture x86.
Result is shown for architecture sparc64
default or selected kernelversion does not have config value CONFIG_ENVCTRL.
Result is shown for kernelversion 5.4.123

SUNW, envctrl support

modulename: envctrl.ko

configname: CONFIG_ENVCTRL

Linux/UltraSPARC Kernel Configuration
└─>General machine setup
└─>SUNW, envctrl support
In linux kernel since version 2.6.12  
Kernel support for temperature and fan monitoring on Sun SME
machines.

To compile this driver as a module, choose M here: the
module will be called envctrl.

source code:
depends
CONFIG_PCI