CONFIG_AKEBONO is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

IBM Akebono (476gtr) Support

modulename: ppc476.ko

configname: CONFIG_AKEBONO

Linux Kernel Configuration
└─>IBM Akebono (476gtr) Support
In linux kernel since version 3.10 (release Date: 2013-06-30)  
This option enables support for the IBM Akebono (476gtr) evaluation board

source code:
arch/powerpc/platforms/44x/ppc476.c

depends
CONFIG_PPC_47x