Add MHUv3 adapter

Use an MHUv3 adapter to forward the calls to the MHU wrapper.

Also remove const from MHUv3 struct's base address so it
can be changed in runtime.

Change-Id: I3ef943716a73081e6386c1ec7b80e255a12ecc91
Signed-off-by: Ziad Elhanafy <ziad.elhanafy@arm.com>
4 files changed