feat(realm): Remove hardcoded MECID

This patch removes the hardcoded fixed MECID with a number which
is continually incremented based on MAX_MECID support.

Signed-off-by: Soby Mathew <soby.mathew@arm.com>
Change-Id: I02b70986d7eef58248abd9c8db0eda20ea32eda0
12 files changed