feat(smc): add test for vendor-specific service

Add test to check vendor-specific el3 service calls.

Change-Id: I981d1cacec8690f57e51a5f05d51b6e437d1eb6a
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
diff --git a/tftf/tests/tests-smc.mk b/tftf/tests/tests-smc.mk
index c3058b2..5d86bf6 100644
--- a/tftf/tests/tests-smc.mk
+++ b/tftf/tests/tests-smc.mk
@@ -9,5 +9,6 @@
 		generic/generic_smc.c				\
 		standard_service/query_std_svc.c		\
 		standard_service/unknown_smc.c 			\
+		el3/query_ven_el3_svc.c				\
 	)