CONFIG_MACH_G3EVM is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

G3EVM board

modulename: board-g3evm.ko

configname: CONFIG_MACH_G3EVM

Linux Kernel Configuration
└─>G3EVM board
In linux kernel since version 2.6.34 (release Date: 2010-05-16)  
source code:
arch/arm/mach-shmobile/board-g3evm.c