modules: cmsis, cmsis_6: only add the intended cmsis module

The current code base is meant to use cmsis for Cortex A and R and
cmsis_6 for Cortex M, but the build system is configured to include the
path for both when Cortex M is selected. This leaves us exposed to PR
using the old headers, that would not get caught in CI but would fail
the build on a project using Cortex M that only has the cmsis_6 module.

Change the cmsis module setting to only include the module files in the
intended case.

Signed-off-by: Fabio Baltieri <[email protected]>

Author: fabiobaltieri

modules/cmsis/CMakeLists.txt

@@ -1,8 +1,7 @@
 # Copyright (c) 2023 Nordic Semiconductor ASA
 # SPDX-License-Identifier: Apache-2.0
 
-add_subdirectory(${ZEPHYR_CURRENT_MODULE_DIR} cmsis)
-
 if(CONFIG_CPU_AARCH32_CORTEX_A OR CONFIG_CPU_AARCH32_CORTEX_R)
+  add_subdirectory(${ZEPHYR_CURRENT_MODULE_DIR} cmsis)
   zephyr_include_directories(.)
 endif()

modules/cmsis_6/CMakeLists.txt

@@ -1,8 +1,7 @@
 # Copyright 2025 Arm Limited and/or its affiliates <[email protected]>
 # SPDX-License-Identifier: Apache-2.0
 
-add_subdirectory(${ZEPHYR_CURRENT_MODULE_DIR} cmsis_6)
-
 if(CONFIG_CPU_CORTEX_M)
+  add_subdirectory(${ZEPHYR_CURRENT_MODULE_DIR} cmsis_6)
   zephyr_include_directories(.)
 endif()