CONFIG_PPC_E500MC is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

e500mc Support

configname: CONFIG_PPC_E500MC

Linux Kernel Configuration
└─>Processor support
└─>e500mc Support
In linux kernel since version 2.6.27 (release Date: 2008-10-09)  
selects
CONFIG_PPC_FPU

depends
CONFIG_E500


is depended by
CONFIG_CORENET_GENERIC