imx: imx8qm: add system off support

Add system power off support for i.MX8QM,
when Linux kernel issues "poweroff" command,
TF-A will send command to inform system
controller to power off whole board according
to board design, tested on i.MX8QM MEK board.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
2 files changed