[MTE] use GTEST_SKIP on non-MTE hw for memtag_stack_test

Bug: 174878242
Change-Id: If980ac4d9bf4bada6e150a5f30c486bdd6de3508
diff --git a/tests/memtag_stack_test.cpp b/tests/memtag_stack_test.cpp
index 1b336bc..84ee8d1 100644
--- a/tests/memtag_stack_test.cpp
+++ b/tests/memtag_stack_test.cpp
@@ -29,7 +29,7 @@
 TEST_P(MemtagStackTest, test) {
 #if defined(__BIONIC__) && defined(__aarch64__)
   if (!mte_supported()) {
-    return;
+    GTEST_SKIP() << "MTE unsupported";
   }
   bool is_static = std::get<1>(GetParam());
   std::string helper =