feat(rng_trap): add tests for FEAT_RNG_TRAP

Added 2 tests that expect a trap to be triggered when a read is
performed on:
1. RNDR register
2. RNDRRS register
The result will be a panic signal and the whole system will halt,
as there is no handler set for such trap.

Signed-off-by: Juan Pablo Conde <juanpablo.conde@arm.com>
Change-Id: Ia979e60a106b394cc09dfdf94115354fb72142d1
diff --git a/include/common/test_helpers.h b/include/common/test_helpers.h
index c51c785..b1349dd 100644
--- a/include/common/test_helpers.h
+++ b/include/common/test_helpers.h
@@ -334,6 +334,15 @@
 		}								\
 	} while (false)
 
+#define SKIP_TEST_IF_RNG_TRAP_NOT_SUPPORTED()					\
+	do {									\
+		if (!is_feat_rng_trap_present()) {				\
+			tftf_testcase_printf("ARMv8.5-RNG_TRAP not"		\
+ 					"supported\n");				\
+			return TEST_RESULT_SKIPPED;				\
+		}								\
+	} while (false)
+
 /* Helper macro to verify if system suspend API is supported */
 #define is_psci_sys_susp_supported()	\
 		(tftf_get_psci_feature_info(SMC_PSCI_SYSTEM_SUSPEND)		\