feat(spmc): enable parsing of messaging methods from manifest

Ensure that the `messaging-methods` entry is populated in
an SP's manifest. Currently only direct messaging is supported
so alert if this does not match the manifest entry.

Signed-off-by: Marc Bonnici <marc.bonnici@arm.com>
Change-Id: I67f1fad71a3507627993a004e0f8579388faf178
1 file changed