CONFIG_ARCH_FOOTBRIDGE is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

FootBridge

configname: CONFIG_ARCH_FOOTBRIDGE

ARM system type
└─>FootBridge
In linux kernel since version 2.6.12  
Support for systems based on the DC21285 companion chip
("FootBridge"), such as the Simtec CATS and the Rebel NetWinder.