remoteproc: imx_rproc: Add support for System Manager CPU API

remoteproc: imx_rproc: Add support for System Manager CPU API

When the System Manager configuration places the M7 core in the same
Logical Machine(LM) as the A55 cores (M7 LM ID equals A55 LM ID), Linux
can control M7 using the CPU protocol API. For more details, see the
previous patch that adds LMM API support.

Changes include:
- Introduce imx_rproc_ops_sm_cpu for CPU API operations.
- Reuse imx_rproc_sm_detect_mode to detect shared LM and set priv->ops to
  imx_rproc_ops_sm_cpu.
- Implement imx_rproc_sm_cpu_{start,stop} to handle M7 start and stop.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Link: https://lore.kernel.org/r/20260109-imx95-rproc-2026-1-8-v6-5-d2fefb36263d@nxp.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>