dt-bindings: display: arm,versatile-tft-panel: Drop erroneous properties in example

The 'arm,versatile-sysreg' node in the example should not have
'#address-cells' and '#size-cells' properties as the child node doesn't
have 'reg'.

Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220810160341.51995-2-robh@kernel.org