CONFIG_BFIN_L2_CACHEABLE is not available for thedefaultarchitecture x86.
Result is shown for architecture blackfin
default or selected kernelversion does not have config value CONFIG_BFIN_L2_CACHEABLE.
Result is shown for kernelversion 5.3.7

Cache L2 SRAM

configname: CONFIG_BFIN_L2_CACHEABLE

Blackfin Kernel Configuration
└─>Blackfin Processor Options
└─>Cache L2 SRAM
In linux kernel since version 2.6.28 (release Date: 2008-12-24)  
Select to make L2 SRAM cacheable in L1 data and instruction cache.