dt-bindings: iio: adc: imx93: drop the 4th interrupt

Per i.MX93 Reference Mannual Rev.4, 12/2013, there is no interrupt 268,
so drop it.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240226130826.3824251-1-peng.fan@oss.nxp.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>