default or selected kernelversion does not have config value CONFIG_ARCH_R9A09G056.
Result is shown for kernelversion 6.16-rc6

ARM64 Platform support for RZ/V2N

configname: CONFIG_ARCH_R9A09G056

Linux Kernel Configuration
└─>Device Drivers
└─>SOC (System On Chip) specific Drivers
└─>Renesas SoC driver support
└─>ARM64 Platform support for RZ/V2N
In linux kernel since version 6.1.145 (release Date: 2025-07-14)  
This enables support for the Renesas RZ/V2N SoC variants.