xen/arm: add reserved-memory regions to the dom0 memory node

xen/arm: add reserved-memory regions to the dom0 memory node

Reserved memory regions are automatically remapped to dom0. Their device
tree nodes are also added to dom0 device tree. However, the dom0 memory
node is not currently extended to cover the reserved memory regions
ranges as required by the spec.  This commit fixes it.

Change make_memory_node to take a  struct meminfo * instead of a
kernel_info. Call it twice for dom0, once to create the first regular
memory node, and the second time to create a second memory node with the
ranges covering reserved-memory regions.

Also, make a small code style fix in make_memory_node.

Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
Acked-by: Julien Grall <julien.grall@arm.com>