backends/cadence cmakelist update to fix reference code build (#7594)

Author: dijopaul

backends/cadence/CMakeLists.txt

@@ -60,9 +60,6 @@ if(EXECUTORCH_CADENCE_CPU_RUNNER)
                                       ${_common_include_directories}
   )
 
-  set(TARGET_DIR reference)
-  add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/${TARGET_DIR}/kernels)
-
   target_link_libraries(
   cadence_runner
   executorch
@@ -78,12 +75,12 @@ endif()
 if(EXECUTORCH_NNLIB_OPT)
   set(TARGET_DIR hifi)
   add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/${TARGET_DIR}/third-party/nnlib)
-  add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/${TARGET_DIR}/kernels)
-endif()
-
-if(EXECUTORCH_FUSION_G3_OPT)
+elseif(EXECUTORCH_FUSION_G3_OPT)
   set(TARGET_DIR fusion_g3)
   add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/${TARGET_DIR}/third-party/nnlib)
+else()
+  set(TARGET_DIR reference)
 endif()
 
+add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/${TARGET_DIR}/kernels)
 add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/${TARGET_DIR}/operators)