CONFIG_SIBYTE_BCM1120 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

CONFIG_SIBYTE_BCM1120 (not configurable)

configname: CONFIG_SIBYTE_BCM1120

Linux/MIPS Kernel Configuration
└─>Machine selection
└─>SIBYTE_BCM1120
In linux kernel since version 2.6.12