fvp_utils: support trace-based code coverage in FVP LAVA jobs

Different test configurations required the trace-based code
coverage pluging [1], however in OpenCI, these are disabled due to
lack of support. This commit enables the support in LAVA jobs,
fetching the coverage trace plugin from the downloads repository
[2]. This patch co-depends on [3] to properly work.

NOTE: 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://gitlab.arm.com/tooling/qa-tools
[2] https://downloads.trustedfirmware.org
[3] https://review.trustedfirmware.org/c/ci/tf-a-job-configs/+/9631

Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
Change-Id: I20c1cb0570169dad1e4c3fd8b6245c820cf5d1ac
diff --git a/script/gen_fvp_tftf_yaml.sh b/script/gen_fvp_tftf_yaml.sh
index e1c874e..a6bab56 100755
--- a/script/gen_fvp_tftf_yaml.sh
+++ b/script/gen_fvp_tftf_yaml.sh
@@ -57,6 +57,8 @@
         url: {CACTUS_SECONDARY}
       cactus_tertiary:
         url: {CACTUS_TERTIARY}
+      coverage_trace_plugin:
+        url: {COVERAGE_TRACE_PLUGIN}
       dtb:
         url: {DTB}
       el3_payload: