dt-bindings: serial: re-order entries to match coding convention

The DT schema coding convention expressed in
Documentation/devicetree/bindings/example-schema.yaml expects entries in
following order:
 - properties, patternProperties
 - required
 - if blocks, allOf with if-blocks
 - additionalProperties/unevaluatedProperties

Re-order few schemas to match the convention to avoid repeating review
comments for new patches using existing code as template.  No functional
changes.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20231016181909.368429-1-krzysztof.kozlowski@linaro.org


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