Switch TF-M branch from "master" to "main"

TF-M development branch is going to be switched from "master" to "main".
Update CI settings to enable tests on "main" branch.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: I3cb37e0f777d117b4ed2081125cfcebd59ed7472
diff --git a/tf-m-coverity.yaml b/tf-m-coverity.yaml
index 4d94ad6..6b20d80 100644
--- a/tf-m-coverity.yaml
+++ b/tf-m-coverity.yaml
@@ -10,10 +10,10 @@
     scm:
         - git:
             url: https://git.trustedfirmware.org/ci/tf-m-ci-scripts.git
-            refspec: +refs/heads/master:refs/remotes/origin/master
+            refspec: +refs/heads/main:refs/remotes/origin/master
             name: origin
             branches:
-                - refs/heads/master
+                - refs/heads/main
             basedir: tf-m-ci-scripts
             skip-tag: true
             shallow-clone: true
@@ -40,13 +40,13 @@
             default: 'https://git.trustedfirmware.org/TF-M/trusted-firmware-m'
         - string:
             name: GERRIT_REFSPEC
-            default: 'refs/heads/master'
+            default: 'refs/heads/main'
         - string:
             name: CI_SCRIPTS_REPO
             default: 'https://git.trustedfirmware.org/ci/tf-m-ci-scripts'
         - string:
             name: CI_SCRIPTS_BRANCH
-            default: 'master'
+            default: 'main'
         - string:
             name: MBEDTLS_VERSION
             default: ''