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.xml b/tftf/tests/tests-smc.xml
index 3633118..b66c7a2 100644
--- a/tftf/tests/tests-smc.xml
+++ b/tftf/tests/tests-smc.xml
@@ -19,6 +19,7 @@
   <testsuite name="Query runtime services" description="Generic queries as defined by the SMCCC">
      <testcase name="Unknown SMC" function="test_unknown_smc" />
      <testcase name="Query Standard Service" function="test_query_std_svc" />
+     <testcase name="Query Vendor-Specific Service" function="test_query_ven_el3_svc" />
   </testsuite>
 
 </testsuites>