xen/dts: Don't add a fake property "name" in the device tree

xen/dts: Don't add a fake property "name" in the device tree

On new Flat Device Tree version, the property "name" may not exist.
The property is never used in Xen code except to set the field "name" of
dt_device_node.

For convenience, remove the fake property. It will save space during the
creation of the dom0 FDT.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>