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

CONFIG_SYS_SUPPORTS_HOTPLUG_CPU (not configurable)

configname: CONFIG_SYS_SUPPORTS_HOTPLUG_CPU

Linux Kernel Configuration
└─>SYS_SUPPORTS_HOTPLUG_CPU
In linux kernel since version 2.6.31 (release Date: 2009-09-09)  
is depended by
CONFIG_MIPS_CPS