staging: mt7621-dts: fix switch0@0 warnings

staging: mt7621-dts: fix switch0@0 warnings

Remove reg property from ports node to fix this warning:

Warning (unit_address_vs_reg): /ethernet@1e100000/mdio-bus/switch0@0/ports: node has a reg or ranges property, but no unit name

Another warning surfaces afterwards. Remove #address-cells and #size-cells
from switch0@0 node to fix this warning:

Warning (avoid_unnecessary_addr_size): /ethernet@1e100000/mdio-bus/switch0@0: unnecessary #address-cells/#size-cells without "ranges" or child "reg" property

Reviewed-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Link: https://lore.kernel.org/r/20220125153903.1469-3-arinc.unal@arinc9.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>