[HACK] configs/refinfra: disable management mode and RAS

Due to changes in upstream TF-A support for SPM, there is failure in
communicating non-trusted software communicating with management
mode software. Until this get resolved, keep management mode and
support for RAS disabled.

Change-Id: I47d63a59e72fa96c42102e50372069c9c12c3fd6
Signed-off-by: Thomas Abraham <thomas.abraham@arm.com>