test(tftf): prevent realm region access from nwd

This change adds a TFTF test attempting an access to a memory region
marked Realm in the GPT.
The PE is expected to trigger a GPF data abort caught by a
custom exception handler.
Exception is trapped at NS-EL2 within TFTF because HCR_EL2.GPF=0
(and SCR_EL3.GPF=0).

Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Change-Id: I05134bb9a3e37fc5478f602844b7a6ad3b8a3293
diff --git a/tftf/tests/tests-invalid-access.mk b/tftf/tests/tests-invalid-access.mk
index a8df96f..f4d23a5 100644
--- a/tftf/tests/tests-invalid-access.mk
+++ b/tftf/tests/tests-invalid-access.mk
@@ -5,3 +5,8 @@
 #
 
 TESTS_SOURCES	+=	tftf/tests/misc_tests/test_invalid_access.c
+
+TESTS_SOURCES	+=							\
+	$(addprefix tftf/tests/runtime_services/realm_payload/,		\
+		realm_payload_test_helpers.c				\
+	)