remoteproc: imx_rproc: support i.MX8MN/P

Add i.MX8MN/P remote processor(Cortex-M7) support, we are using ARM
SMCCC to start/stop M core, not using regmap interface.

Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/1620274123-1461-9-git-send-email-peng.fan@oss.nxp.com


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>