CONFIG_SOC_IMXRT is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

i.MXRT support

modulename: mach-imxrt.ko

configname: CONFIG_SOC_IMXRT

Linux Kernel Configuration
└─>Freescale i.MX family
└─>i.MXRT support
In linux kernel since version 4.14.326 (release Date: 2023-09-23)  
This enables support for Freescale i.MXRT Crossover processor.

source code: