Cleanup: remove *.datax files with CMake

Unrelated to other commits in this PR, except when running manual tests
I kept noticing these files where left over.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 454fe5a..6d54d7c 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -85,6 +85,8 @@
             ${CMAKE_CURRENT_SOURCE_DIR}/suites/host_test.function
             ${CMAKE_CURRENT_SOURCE_DIR}/suites/helpers.function
             ${mbedtls_target}
+        BYPRODUCTS
+            test_suite_${data_name}.datax
     )
 
     add_executable(test_suite_${data_name} test_suite_${data_name}.c $<TARGET_OBJECTS:mbedtls_test>)