cmake only init cmake_hexagon if used

CMakeLists.txt

@@ -124,7 +124,6 @@ execute_process(
 	WORKING_DIRECTORY ${PX4_SOURCE_DIR}
 	)
 
-px4_add_git_submodule(TARGET git_cmake_hexagon PATH "cmake/cmake_hexagon")
 px4_add_git_submodule(TARGET git_uavcan_board_ident PATH "cmake/configs/uavcan_board_ident")
 px4_add_git_submodule(TARGET git_ecl PATH "src/lib/ecl")
 px4_add_git_submodule(TARGET git_matrix PATH "src/lib/matrix")

cmake/configs/posix_sdflight_default.cmake

+include(common/px4_git)
+px4_add_git_submodule(TARGET git_cmake_hexagon PATH "cmake/cmake_hexagon")
+
 include(posix/px4_impl_posix)
 
 # Get $QC_SOC_TARGET from environment if existing.
@@ -83,4 +86,4 @@ set(config_module_list
 	platforms/common
 	platforms/posix/px4_layer
 	platforms/posix/work_queue
-	)
\ No newline at end of file
+	)

cmake/configs/posix_sdflight_legacy.cmake

+include(common/px4_git)
+px4_add_git_submodule(TARGET git_cmake_hexagon PATH "cmake/cmake_hexagon")
+
 include(posix/px4_impl_posix)
 
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${PX4_SOURCE_DIR}/cmake/cmake_hexagon")

cmake/configs/qurt_sdflight_default.cmake

+include(common/px4_git)
+px4_add_git_submodule(TARGET git_cmake_hexagon PATH "cmake/cmake_hexagon")
+
 include(qurt/px4_impl_qurt)
 
 if ("$ENV{HEXAGON_SDK_ROOT}" STREQUAL "")

cmake/configs/qurt_sdflight_legacy.cmake

+include(common/px4_git)
+px4_add_git_submodule(TARGET git_cmake_hexagon PATH "cmake/cmake_hexagon")
+
 include(qurt/px4_impl_qurt)
 
 if ("$ENV{HEXAGON_SDK_ROOT}" STREQUAL "")