refactor(tc): define PLATFORM_TESTS for scale

For scalability when we add more tests in the future, add PLATFORM_TESTS
macro when specific test flags, i.e. PLATFORM_TEST_NV_COUNTERS, are
defined.

Change-Id: Icb875a171dde673fca9fcf66624ac55383e7b641
Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>
diff --git a/plat/arm/board/tc/tc_bl31_setup.c b/plat/arm/board/tc/tc_bl31_setup.c
index 8ad1d30..d2a14d2 100644
--- a/plat/arm/board/tc/tc_bl31_setup.c
+++ b/plat/arm/board/tc/tc_bl31_setup.c
@@ -53,7 +53,7 @@
 {
 	arm_bl31_platform_setup();
 
-#if defined(PLATFORM_TEST_NV_COUNTERS) || defined(PLATFORM_TEST_TFM_TESTSUITE)
+#ifdef PLATFORM_TESTS
 #ifdef PLATFORM_TEST_NV_COUNTERS
 	nv_counter_test();
 #elif PLATFORM_TEST_TFM_TESTSUITE