CONFIG_ARCH_R8A7778 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

R-Car M1A (R8A77781)

modulename: clk-r8a7778.ko

and/or

setup-r8a7778.ko

and/or

clock-r8a7778.ko

configname: CONFIG_ARCH_R8A7778

Linux Kernel Configuration
└─>Renesas ARM SoCs
└─>R-Car M1A (R8A77781)
In linux kernel since version 3.1 (release Date: 2011-10-24)  
source code:
arch/arm/mach-shmobile/setup-r8a7778.c