xen/arm: domain_build: Plumb for different mapping attributes

xen/arm: domain_build: Plumb for different mapping attributes

Add plumbing for passing around mapping attributes.
Nodes that don't specifically state their type will inherit
their type from their parent.

This is in preparation for allowing us to differentiate the attributes
for specific device nodes.

We still use the same DEVICE mappings for all nodes so this
patch has no functional change.

Acked-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>