default or selected kernelversion does not have config value CONFIG_EARLY_PRINTK_MRST.
Result is shown for kernelversion 6.2.5

Early printk for MRST platform support

modulename: early_printk_mrst.ko

configname: CONFIG_EARLY_PRINTK_MRST

Linux Kernel Configuration
└─>Kernel hacking
└─>Early printk for MRST platform support
In linux kernel since version 2.6.37 (release Date: 2011-01-04)  
source code: