Add three methods IMX_RPROC_NONE(no need start/stop), IMX_RPROC_MMIO
(start/stop through mmio) and IMX_RPROC_SMC(start/stop through ARM SMCCC).

The current SoCs supported are all using IMX_RPROC_MMIO.
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/1620274123-1461-6-git-send-email-peng.fan@oss.nxp.comSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>