dt-bindings: serial: 8250_omap: Drop redundant properties

dt-bindings: serial: 8250_omap: Drop redundant properties

The binding references in-kernel serial.yaml, so there is no need to
explicitly list its properties.  Note that rts-gpio is also redundant
because DTS should be simply converted to -gpios variants.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20250514125127.56149-2-krzysztof.kozlowski@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>