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

CONFIG_FORCE_SMP (not configurable)

configname: CONFIG_FORCE_SMP

Linux Kernel Configuration
└─>Processor support
└─>FORCE_SMP
In linux kernel since version 3.10 (release Date: 2013-06-30)  
selects
CONFIG_SMP