dt-bindings: serial: st,stm32-uart: drop common properties

The binding references serial and rs485 schemas, so there is no need to
list their properties.  Simplify a bit by removing unneeded entries.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230124091916.45054-8-krzysztof.kozlowski@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>