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

CONFIG_FSL_BOOKE (not configurable)

configname: CONFIG_FSL_BOOKE

Linux Kernel Configuration
└─>Processor support
└─>FSL_BOOKE
In linux kernel since version 2.6.15 (release Date: 2006-01-02)