imx: imx8qx: add domain suspend/resume support

Add domain suspend/resume support, Linux kernel
can "echo mem > /sys/power/state" to put system
into suspend mode, all CPUs and cluster will be
powered off and can be waked up if irq pending
in GIC, tested on i.MX8QX MEK board.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
diff --git a/plat/imx/common/imx8_psci.c b/plat/imx/common/imx8_psci.c
index 37eda3e..22a531b 100644
--- a/plat/imx/common/imx8_psci.c
+++ b/plat/imx/common/imx8_psci.c
@@ -27,3 +27,20 @@
 	panic();
 }
 
+int imx_validate_power_state(unsigned int power_state,
+			 psci_power_state_t *req_state)
+{
+	/* TODO */
+	return PSCI_E_INVALID_PARAMS;
+}
+
+void imx_get_sys_suspend_power_state(psci_power_state_t *req_state)
+{
+	unsigned int i;
+
+	/* CPU & cluster off, system in retention */
+	for (i = MPIDR_AFFLVL0; i < PLAT_MAX_PWR_LVL; i++)
+		req_state->pwr_domain_state[i] = PLAT_MAX_OFF_STATE;
+	req_state->pwr_domain_state[PLAT_MAX_PWR_LVL] = PLAT_MAX_RET_STATE;
+}
+