feat(tc): initialize MHU channels with RSE

Initialize MHU channels between TF-A and RSE, this is a preparation
for later sending messages to RSE.

Signed-off-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Icen Zeyada <Icen.Zeyada2@arm.com>
Change-Id: I66095cafcc1d48249cf957a49dc1dad3059a0010
2 files changed