samples: dac: Enable dac sample on mimxrt1180_evk

DAC output is available on connector J12 pin 4.

Building and Running for MIMXRT1180-EVK

=======================================

The sample can be built and executed for the :zephyr:board:`mimxrt1180_evk` as

follows:

.. zephyr-app-commands::

   :zephyr-app: samples/drivers/dac

   :board: mimxrt1180_evk/mimxrt1189/cm33

   :goals: flash

   :compact:

.. zephyr-app-commands::

   :zephyr-app: samples/drivers/dac

   :board: mimxrt1180_evk/mimxrt1189/cm7

   :goals: flash

   :compact:

Connect J10 pin 1-2., the DAC output is available on TP9.

Sample output

=============

/*

 * Copyright 2025 NXP

 *

 * SPDX-License-Identifier: Apache-2.0

 */

/ {

	zephyr,user {

		dac = <&dac>;

		dac-channel-id = <0>;

		dac-resolution = <12>;

	};

};

/*

 * Copyright 2025 NXP

 *

 * SPDX-License-Identifier: Apache-2.0

 */

/ {

	zephyr,user {

		dac = <&dac>;

		dac-channel-id = <0>;

		dac-resolution = <12>;

	};

};