Removed unused function in Noop cache adapter
Removed unused function in Noop cache adapter

sohelrana820/flysystem,dstockto/flysystem,sachintaware/flysystem,barryvdh/flysystem,twistor/flysystem,farmisen/flysystem,mapyo/flysystem,dshafik/flysystem,oswaldderiemaecker/flysystem,CarsonF/flysystem,rossriley/flysystem,mhlavac/flysystem,hannesvdvreken/flysystem,twistor/flysystem,nao-pon/flysystem,mhlavac/flysystem,Amrit01/flysystem