Update references to mbedtls_dev

Change these to point to the new mbedtls_framework module in the
framework submodule.

Signed-off-by: David Horstmann <david.horstmann@arm.com>
diff --git a/tests/scripts/generate_test_cert_macros.py b/tests/scripts/generate_test_cert_macros.py
index 07c5b7d..14270e0 100755
--- a/tests/scripts/generate_test_cert_macros.py
+++ b/tests/scripts/generate_test_cert_macros.py
@@ -14,7 +14,7 @@
 import argparse
 import jinja2
 import scripts_path # pylint: disable=unused-import
-from mbedtls_dev.build_tree import guess_project_root
+from mbedtls_framework.build_tree import guess_project_root
 
 TEST_DIR = os.path.join(guess_project_root(), 'tests')
 DATA_FILES_PATH = os.path.join(TEST_DIR, 'data_files')