refactor: add new test-suite 'tests-timer-stress'

Moved 'Stress test timer framework' as part of 'tests-extensive' suite
by creating a separate test suite for timers, i.e. tests-timer-stress.

Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
Change-Id: Ibdad88e81fba55333c0ad17cc9c10d24d97e6c7e
diff --git a/tftf/tests/tests-timer-stress.xml b/tftf/tests/tests-timer-stress.xml
new file mode 100644
index 0000000..e461e90
--- /dev/null
+++ b/tftf/tests/tests-timer-stress.xml
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<!--
+  Copyright (c) 2022, Arm Limited. All rights reserved.
+
+  SPDX-License-Identifier: BSD-3-Clause
+-->
+
+<testsuites>
+
+  <testsuite name="Stress tests" description="Validate all stress tests">
+     <testcase name="Stress test the timer framework" function="stress_test_timer_framework" />
+  </testsuite>
+
+</testsuites>