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/scripts/generate_driver_wrappers.py b/scripts/generate_driver_wrappers.py
index 624ab81..ec79c4e 100755
--- a/scripts/generate_driver_wrappers.py
+++ b/scripts/generate_driver_wrappers.py
@@ -17,7 +17,7 @@
 import argparse
 import jsonschema
 import jinja2
-from mbedtls_dev import build_tree
+from mbedtls_framework import build_tree
 
 JSONSchema = NewType('JSONSchema', object)
 # The Driver is an Object, but practically it's indexable and can called a dictionary to