Fix: change linux components to use branches

In the GitLab repository of the arm_ffa_user and arm_ffa_tee drivers
there are overloaded tag and branch names which makes CMake v3.18
unable to clone these.
Change the external components making this repo available locally to
use explicit branch names to work around the issue.

Change-Id: Ie94b65fc0f00d70d04e797240f551f79cc16bb39
Signed-off-by: Gyorgy Szing <Gyorgy.Szing@arm.com>
2 files changed