lava_helper: enable trace-based code coverage in FVP MPS2 jobs

Enable trace-based code coverage supportin in FVP MPS2 LAVA jobs,
where LAVA would fetch the coverage trace plugin from the downloads
repository [1].

This patch does not cover the extraction of trace logs from LAVA
into Jenkins, so the latter can convert logs into human-friendly LCOV
html reports. This is WIP and will be coverered in a separate patch.

[1] https://downloads.trustedfirmware.org

Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
Change-Id: I81a8aaf3edaa4fd84e46526ed3d29ad94aa23a1b
diff --git a/lava_helper/lava_helper_configs.py b/lava_helper/lava_helper_configs.py
index 3ddb364..1f95d12 100644
--- a/lava_helper/lava_helper_configs.py
+++ b/lava_helper/lava_helper_configs.py
@@ -19,6 +19,8 @@
 __project__ = "Trusted Firmware-M Open CI"
 __version__ = "1.2.0"
 
+tf_downloads="https://downloads.trustedfirmware.org"
+coverage_trace_plugin=tf_downloads + "/coverage-plugin/qa-tools/coverage-tool/coverage-plugin/coverage_trace.so"
 
 def lava_gen_get_config_subset(config,
                                default=True,