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>

plat/imx/imx8qm/imx8qm_psci.c

@@ -94,6 +94,7 @@ static const plat_psci_ops_t imx_plat_psci_ops = {
 	.pwr_domain_on = imx_pwr_domain_on,
 	.pwr_domain_on_finish = imx_pwr_domain_on_finish,
 	.validate_ns_entrypoint = imx_validate_ns_entrypoint,
+	.system_off = imx_system_off,
 };
 
 int plat_setup_psci_ops(uintptr_t sec_entrypoint,

plat/imx/imx8qm/platform.mk

@@ -21,6 +21,7 @@ BL31_SOURCES		+=	plat/imx/common/lpuart_console.S	\
 				plat/imx/imx8qm/imx8qm_bl31_setup.c	\
 				plat/imx/imx8qm/imx8qm_psci.c		\
 				plat/imx/common/imx8_topology.c		\
+				plat/imx/common/imx8_psci.c		\
 				lib/xlat_tables/aarch64/xlat_tables.c		\
 				lib/xlat_tables/xlat_tables_common.c		\
 				lib/cpus/aarch64/cortex_a53.S			\