scp: Update maintainers references to Gitlab
Update the maintainers' references from Github URLs to Gitlab ones. At the same time, update Platform Maintainers and remove all the users' email address.
Signed-off-by: Nicola Mazzucato nicola.mazzucato@arm.com Change-Id: If14ad62067c5148d31436f40657ff43d0e063c09