ASoC: dt-bindings: davinci-mcasp: Fix interrupt properties

Combinations of "tx" alone, "rx" alone and "tx", "rx" together are
supposedly valid (see link below), which is not the case today as "rx"
alone is not accepted by the current binding.

Let's rework the two interrupt properties to expose all correct
possibilities.

Cc: Péter Ujfalusi <peter.ujfalusi@gmail.com>
Link: https://lore.kernel.org/linux-sound/20241003102552.2c11840e@xps-13/T/#m277fce1d49c50d94e071f7890aed472fa2c64052


Fixes: 8be90641 ("ASoC: dt-bindings: davinci-mcasp: convert McASP bindings to yaml schema")
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://patch.msgid.link/20241003083611.461894-1-miquel.raynal@bootlin.com


Signed-off-by: Mark Brown <broonie@kernel.org>