tf-m-coverity.yaml: bump coverity version to 2020.09

Besides bumping the version from 2019.03 to 2020.09, a new parameter
is introduced, COVERITY_VERSION, indicating the coverity version, this
way, the version is not hardcoded into the builder's shell script.

This patch fixes recent failues (37-44) at [1]. Tested at staging at [2]

[1] https://ci.trustedfirmware.org/job/tf-m-coverity/
[2] https://ci.staging.trustedfirmware.org/job/lsandov1-tf-m-coverity/75/console

Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
Change-Id: I735f535856ca5629f3e45385a09e98a3e56e66cb
diff --git a/tf-m-coverity.yaml b/tf-m-coverity.yaml
index 1741cfa..8384245 100644
--- a/tf-m-coverity.yaml
+++ b/tf-m-coverity.yaml
@@ -62,9 +62,12 @@
         - string:
             name: TF_GERRIT_REFSPEC
             default: '+refs/heads/master:refs/remotes/origin/master'
+        - string:
+            name: COVERITY_VERSION
+            default: '2020.09'
         - bool:
             name: UPLOAD_TO_COVERITY_SCAN_ONLINE
-            default: true
+            default: false
     scm:
         - tf-m-ci-scripts
         - trusted-firmware-m
@@ -80,7 +83,6 @@
             set -e
 
             # Fetch coverity tool and untar it
-            COVERITY_VERSION=2019.03
             cd ${WORKSPACE}
             wget https://scan.coverity.com/download/linux64 \
                 --quiet \