remoteproc: imx_rproc: Enable PM runtime support unconditionally

remoteproc: imx_rproc: Enable PM runtime support unconditionally

PM runtime support is safe and applicable across all i.MX platforms, not
just those using the SCU API. Remove the conditional check and enable PM
runtime unconditionally to simplify the code and ensure consistent power
management behavior.

Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20251024-imx_rproc_c4-v4-3-af83ed3fdbba@nxp.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>