versal_pm_request() and invoke_smc() are almost the same. Only one
difference is that versal_pm_request is adding PM_SIP_SVC offset to api_id.
The patch is moving platform implementation to firmware driver code for
synchronization.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Luca Ceresoli <luca@lucaceresoli.net>