CONFIG_H8S2678 is not available for thedefaultarchitecture x86.
Result is shown for architecture h8300

CONFIG_H8S2678 (not configurable)

modulename: clk-h8s2678.ko

configname: CONFIG_H8S2678

Linux Kernel Configuration
└─>H8S2678
In linux kernel since version 2.6.12  
source code:
drivers/clk/h8300/clk-h8s2678.c