mips: lantiq: danube: add missing device_type in pci node

mips: lantiq: danube: add missing device_type in pci node

[ Upstream commit d66949a1875352d2ddd52b144333288952a9e36f ]

This fixes the following warning:
arch/mips/boot/dts/lantiq/danube_easy50712.dtb: pci@e105400 (lantiq,pci-xway): 'device_type' is a required property
	from schema $id: http://devicetree.org/schemas/pci/pci-bus-common.yaml#

Signed-off-by: Aleksander Jan Bajkowski <olek2@wp.pl>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>