remove dead code

ScriptableRenderPipeline/Core/CoreRP/TextureCache.cs

             get
             {
                 var format = TextureFormat.RGBAHalf;
-
-//                // On editor the texture is uncompressed when operating against mobile build targets
-//#if UNITY_2017_2_OR_NEWER
-//#else
-//                if (SystemInfo.SupportsTextureFormat(probeFormat) && !TextureCache.isMobileBuildTarget)
-//                    format = probeFormat;
-//#endif
 
                 return format;
             }
         {
             get
             {
-//#if UNITY_2017_2_OR_NEWER
-//#else
-//                return (SystemInfo.supportsCubemapArrayTextures && !TextureCache.isMobileBuildTarget);
-//#endif
             }
         }