Add tests for Errata management firmware interface.

Add tests to confirm that the em_version, em_features and
em_cpu_erratum_features calls conform to the errata abi spec.

Signed-off-by: Sona Mathew <SonaRebecca.Mathew@arm.com>
Change-Id: I8395026acc004a10d8c2c17ec689f4e0752143d8
11 files changed