CONFIG_PPC_86xx is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

CONFIG_PPC_86xx (not configurable)

configname: CONFIG_PPC_86xx

Linux Kernel Configuration
└─>PPC_86xx
In linux kernel since version 2.6.18 (release Date: 2006-09-19)  

depends
 or CONFIG_6xx or CONFIG_PPC_BOOK3S_32