CONFIG_DEBUG_ZTE_ZX is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_DEBUG_ZTE_ZX.
Result is shown for kernelversion 6.9.9

Use ZTE ZX UART

configname: CONFIG_DEBUG_ZTE_ZX

Kernel low-level debugging port
└─>Use ZTE ZX UART
In linux kernel since version 4.1 (release Date: 2015-06-21)  
Say Y here if you are enabling ZTE ZX296702 SOC and need
debug uart support.

This option is preferred over the platform specific
options; the platform specific options are deprecated
and will be soon removed.