arm64: dts: juno: Add separate SCMI variants

While Juno's SCP firmware initially spoke the SCPI protocol, binary
releases since 2018, and the newer open-source codebase, only speak SCMI
and thus aren't particularly compatibile with the DTs we currently have
upstream. Add a parallel set of variant DTs for boards with up-to-date
firmware, replacing the SCPI parts with their new SCMI equivalents.

Link: https://lore.kernel.org/r/f3516815104f951a05fc0f799681f77d7968f6ac.1645125063.git.robin.murphy@arm.com
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>