CMake: Fix build failure due to nanostack drivers move

connectivity/drivers/802.15.4_RF/CMakeLists.txt

@@ -1,6 +1,8 @@
 # Copyright (c) 2020 ARM Limited. All rights reserved.
 # SPDX-License-Identifier: Apache-2.0
 
+mbed_add_cmake_directory_if_labels("TARGET")
+
 add_subdirectory(atmel-rf-driver)
 add_subdirectory(mcr20a-rf-driver)
 add_subdirectory(stm-s2lp-rf-driver)

features/nanostack/nanostack-interface/CMakeLists.txt

@@ -1,14 +1,12 @@
 # Copyright (c) 2020 ARM Limited. All rights reserved.
 # SPDX-License-Identifier: Apache-2.0
 
-add_subdirectory(targets)
-
-target_sources(mbed-os
-    PRIVATE
-        Nanostack.cpp
-)
-
 target_include_directories(mbed-os
     PUBLIC
         ${CMAKE_CURRENT_SOURCE_DIR}
 )
+
+target_sources(mbed-os
+    PRIVATE
+        Nanostack.cpp
+)

features/nanostack/nanostack-interface/targets/TARGET_Silicon_Labs/CMakeLists.txt

@@ -1,4 +0,0 @@
-# Copyright (c) 2020 ARM Limited. All rights reserved.
-# SPDX-License-Identifier: Apache-2.0
-
-mbed_add_cmake_directory_if_labels("TARGET")