CS315: Enable Regression tests for Corstone-315

Signed-off-by: Gergely Korcsák <gergely.korcsak@arm.com>
Change-Id: Ied1a769cbb27a00c751df11e37fd45c0df0f8247
diff --git a/build_helper/build_helper_configs.py b/build_helper/build_helper_configs.py
index 6d25d40..b29b2c2 100755
--- a/build_helper/build_helper_configs.py
+++ b/build_helper/build_helper_configs.py
@@ -880,7 +880,7 @@
                 "tfm_platform":     ["arm/mps4/corstone315"],
                 "compiler":         ["GCC_10_3", "ARMCLANG_6_21"],
                 "isolation_level":  ["1"],
-                "test_regression":  ["OFF"],
+                "test_regression":  ["OFF", "RegBL2, RegS, RegNS"],
                 "test_psa_api":     ["OFF"],
                 "cmake_build_type": ["Debug", "Release"],
                 "with_bl2":         [True],