ASoC: imx-hdmi: remove cpu_pdev related code

If a defer probe happens for the cpu device, the return value for
cpu_pdev "ret = -EINVAL" breaks defer probe. As the cpus->dai_name
can be replaced by cpus->of_node, to simplify the code, remove related
code for cpu_pdev.

Fixes: 6a5f850a ("ASoC: fsl: Add imx-hdmi machine driver")
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Message-ID: <20250820031641.2158261-1-shengjiu.wang@nxp.com>
Signed-off-by: Mark Brown <broonie@kernel.org>