dt-bindings: net: dsa: qca8k: remove address-cells and size-cells from switch node

The children of the switch node don't have a unit address, and therefore
should not need the #address-cells or #size-cells entries. Fix the example
schemas accordingly.

Suggested-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Colin Foster <colin.foster@in-advantage.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>