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/check_files.py b/tests/scripts/check_files.py
index d5a4b92..45d7895 100755
--- a/tests/scripts/check_files.py
+++ b/tests/scripts/check_files.py
@@ -24,7 +24,7 @@
     pass
 
 import scripts_path # pylint: disable=unused-import
-from mbedtls_dev import build_tree
+from mbedtls_framework import build_tree
 
 
 class FileIssueTracker: