tests/avocado: add explicit timeout for s390 TCG tests

We don't want to rely on the soon to be reduced default time. These
tests are still slow for something we want to run in CI though.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20220914155950.804707-5-alex.bennee@linaro.org>

tests/avocado/boot_linux.py

@@ -130,6 +130,8 @@ class BootLinuxS390X(LinuxTest):
     :avocado: tags=arch:s390x
     """
 
+    timeout = 240
+
     @skipIf(os.getenv('GITLAB_CI'), 'Running on GitLab')
     def test_s390_ccw_virtio_tcg(self):
         """