The Juno development platform has an external expansion bus which can
be used for additional hardware (e.g. LogicTile Express daughterboards).

Add this bus to the Juno base device-tree.
Acked-by: Liviu Dudau <Liviu.Dudau@arm.com>
Signed-off-by: Brian Starkey <brian.starkey@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>