remoteproc: imx_dsp_rproc: Simplify power domain attach and error handling

remoteproc: imx_dsp_rproc: Simplify power domain attach and error handling

Refactor imx_dsp_attach_pm_domains() to use devm_pm_domain_attach_list()
directly, removing manual detach logic and simplifying resource management.

Also replace verbose error handling in imx_dsp_rproc_probe() with
dev_err_probe() for cleaner and more consistent error reporting.

No functional changes.

Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Reviewed-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Reviewed-by: Iuliana Prodan <iuliana.prodan@nxp.com>
Tested-by: Iuliana Prodan <iuliana.prodan@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20251119-imx-dsp-2025-11-19-v4-1-adafd342d07b@nxp.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>