CONFIG_MIGHT_HAVE_CACHE_L2X0 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

CONFIG_MIGHT_HAVE_CACHE_L2X0 (not configurable)

configname: CONFIG_MIGHT_HAVE_CACHE_L2X0

Linux Kernel Configuration
└─>MIGHT_HAVE_CACHE_L2X0
In linux kernel since version 3.1 (release Date: 2011-10-24)  
This option should be selected by machines which have a L2x0
or PL310 cache controller, but where its use is optional.

The only effect of this option is to make CACHE_L2X0 and
related options available to the user for configuration.

Boards or SoCs which always require the cache controller
support to be present should select CACHE_L2X0 directly
instead of this option, thus preventing the user from
inadvertently configuring a broken kernel.