We appear to have missed the Set/Way CMOs when adding MTE support.
Not that we really expect anyone to use them, but you never know
what stupidity some people can come up with...

Treat these mostly like we deal with the classic S/W CMOs, only
with an additional check that MTE really is enabled.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20230515204601.1270428-3-maz@kernel.org