CONFIG_CACHE_L2X0 is not available for thedefaultarchitecture x86.
Result is shown for architecture arm

Enable the L2x0 outer cache controller

modulename: cache-l2x0.ko

configname: CONFIG_CACHE_L2X0

Linux Kernel Configuration
└─>Enable the L2x0 outer cache controller
In linux kernel since version 2.6.21 (release Date: 2007-04-25)  
This option enables the L2x0 PrimeCell.

source code:
arch/arm/mm/cache-l2x0.c