arm64: dts: layerscape: rename aux-bus to bus

arm64: dts: layerscape: rename aux-bus to bus

The node name 'aux-bus' is special word. It invokes dp-aux-bus.yaml binding
check. Simple change to 'bus' to fix below warning.

aux-bus: '#address-cells', '#size-cells', 'compatible', 'dma-ranges', 'ranges', 'sata@3200000', 'usb@2f00000', 'usb@3000000', 'usb@3100000' do not match any of the regexes: 'pinctrl-[0-9]+'
	from schema $id: http://devicetree.org/schemas/display/dp-aux-bus.yaml#

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>