Enable test generation from bignum_mod.py

Signed-off-by: Werner Lewis <werner.lewis@arm.com>
diff --git a/tests/scripts/generate_bignum_tests.py b/tests/scripts/generate_bignum_tests.py
index c3058e9..0b84711 100755
--- a/tests/scripts/generate_bignum_tests.py
+++ b/tests/scripts/generate_bignum_tests.py
@@ -66,7 +66,7 @@
 # Import modules containing additional test classes
 # Test function classes in these modules will be registered by
 # the framework
-from mbedtls_dev import bignum_core, bignum_mod_raw # pylint: disable=unused-import
+from mbedtls_dev import bignum_core, bignum_mod_raw, bignum_mod # pylint: disable=unused-import
 
 class BignumTarget(test_data_generation.BaseTarget):
     #pylint: disable=too-few-public-methods