ARM: dts: marvell: Fix some common switch mistakes

Fix some errors in the Marvell MV88E6xxx switch descriptions:
- The top node had no address size or cells.
- switch0@0 is not OK, should be ethernet-switch@0.
- The ports node should be named ethernet-ports
- The ethernet-ports node should have port@0 etc children, no
  plural "ports" in the children.
- Ports should be named ethernet-port@0 etc
- PHYs should be named ethernet-phy@0 etc

This serves as an example of fixes needed for introducing a
schema for the bindings, but the patch can simply be applied.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>