ci: update tfa_downloads path

Use https://downloads.trustedfirmware.org/tf-a instead
of artifactory.

Signed-off-by: Ryan Everett <ryan.everett@arm.com>
Change-Id: Ie443547585f8c9916905fecd3dbeb956718d784d
diff --git a/arm-env.sh b/arm-env.sh
index a4c24e9..25999f9 100644
--- a/arm-env.sh
+++ b/arm-env.sh
@@ -11,7 +11,7 @@
 
 nfs_volume="/arm"
 jenkins_url="https://jenkins.oss.arm.com"
-tfa_downloads="https://artifactory.eu02.arm.com/artifactory/trustedfirmware.downloads"
+tfa_downloads="https://downloads.trustedfirmware.org/tf-a"
 ci_env="armci"
 
 # Source repositories.