CONFIG_ARCH_U300 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_ARCH_U300.
Result is shown for kernelversion 6.9.5

ST-Ericsson U300 Series

modulename: clk-u300.ko

configname: CONFIG_ARCH_U300

Linux Kernel Configuration
└─>ST-Ericsson U300 Series
In linux kernel since version 2.6.31 (release Date: 2009-09-09)  
Support for ST-Ericsson U300 series mobile platforms.

source code: