dev-arm: Implement Arm MHU (Message Handling Unit)

JIRA: https://gem5.atlassian.net/browse/GEM5-768

Change-Id: I895eba1a3421746a602e6a4f88916da9054169a8
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/34378
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
6 files changed