arm64: dts: imx8qm-sof-wm8960: Remove FSL DAI generic node

arm64: dts: imx8qm-sof-wm8960: Remove FSL DAI generic node

This removes FSL DAI generic node as suggested by upstream
community review and move resources handling for DAIs under
DSP platform node.

So, pinctrl, power domains and clocks are now under dsp node.

Notice that, now DAI links looks like this:
cpu {
    sound-dai = <&dsp 1>;
};
codec {
    sound-dai = <&wm8960>;
};

See how CPU sound-dai gets an additional CELL for DAI index as
defined by the array imx8_dai from sound/soc/sof/imx/imx8.c

Here we need SAI1 index which is 1.

Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>