ARM: dts: aspeed-g6: Drop cells properties from ethernet nodes

ARM: dts: aspeed-g6: Drop cells properties from ethernet nodes

These are not specified in the binding and produce warnings such as
the following:

 arch/arm/boot/dts/aspeed/aspeed-g6.dtsi:254.27-262.5: Warning
 (avoid_unnecessary_addr_size): /ahb/ethernet@1e670000: unnecessary
 #address-cells/#size-cells without "ranges", "dma-ranges" or child
 "reg" property

 arch/arm/boot/dts/aspeed/aspeed-g6.dtsi:264.27-272.5: Warning
 (avoid_unnecessary_addr_size): /ahb/ethernet@1e690000: unnecessary
 #address-cells/#size-cells without "ranges", "dma-ranges" or child
 "reg" property

 arch/arm/boot/dts/aspeed/aspeed-ast2600-evb-a1.dtb: ethernet@1e660000:
 Unevaluated properties are not allowed ('#address-cells', '#size-cells'
 were unexpected)

Link: https://lore.kernel.org/r/20240802-dt-warnings-bmc-dts-cleanups-v1-7-1cb1378e5fcd@codeconstruct.com.au
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>