Per davicom,dm9000.yaml, the Ethernet node name should be 'ethernet'.

Change it to fix the following schema warning:

imx1-apf9328.dtb: eth@4,c00000: $nodename:0: 'eth@4,c00000' does not match '^ethernet(@.*)?$'
	from schema $id: http://devicetree.org/schemas/net/davicom,dm9000.yaml#Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>