Fixing issue on building reference code in Cmakelist

Author: dijopaul

backends/cadence/CMakeLists.txt

@@ -86,6 +86,7 @@ elseif(EXECUTORCH_FUSION_G3_OPT)
   ${EXECUTORCH_ROOT}/runtime/core/portable_type/c10)
 else()
   set(TARGET_DIR reference)
+  add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/${TARGET_DIR}/kernels)
 endif()