From R01UH0914EJ0120 Rev.1.20 HW manual, for full duplex channels
(SSI0/1/3) dma_rt interrupt has now being marked as reserved and similarly
for half duplex channel (SSI2) dma_rx and dma_tx interrupts have now being
marked as reserved (this applies to RZ/G2L and alike SoC's). This patch
updates the binding doc to match the same.

While at it also updated the example node.
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230217185225.43310-2-prabhakar.mahadev-lad.rj@bp.renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>