CONFIG_MICROBLAZE is not available for thedefaultarchitecture x86.
Result is shown for architecture microblaze

CONFIG_MICROBLAZE (not configurable)

modulename: setup-bus.ko

configname: CONFIG_MICROBLAZE

Linux/Microblaze Kernel Configuration
└─>MICROBLAZE
In linux kernel since version 2.6.30 (release Date: 2009-06-09)  

is selected by
CONFIG_SPI_XILINX