CONFIG_CPU_S5P6450 is not available for the selected architecture x86.
Result is shown for architecture arm
CONFIG_CPU_S5P6450 (not configurable)
modulename: clock-s5p6450.ko
configname: CONFIG_CPU_S5P6450
Linux Kernel Configuration
└─>CPU_S5P6450
In linux kernel since version 2.6.37 (release Date: 2011-01-04)
Enable S5P6450 CPU support