default or selected kernelversion does not have config value CONFIG_SPI_NUC900.
Result is shown for kernelversion 6.9.9

Nuvoton NUC900 series SPI

modulename: spi-nuc900.ko

configname: CONFIG_SPI_NUC900

Linux Kernel Configuration
└─>Device Drivers
└─>SPI support
└─>Nuvoton NUC900 series SPI
In linux kernel since version 2.6.33 (release Date: 2010-02-24)  
SPI driver for Nuvoton NUC900 series ARM SoCs

source code:
drivers/spi/spi-nuc900.c