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/include/plat_imx8.h b/plat/imx/common/include/plat_imx8.h
index 3b5f4ec..a333bfb 100644
--- a/plat/imx/common/include/plat_imx8.h
+++ b/plat/imx/common/include/plat_imx8.h
@@ -8,6 +8,7 @@
 #define __PLAT_IMX8_H__
 
 #include <gicv3.h>
+#include <psci.h>
 
 unsigned int plat_calc_core_pos(uint64_t mpidr);
 void imx_mailbox_init(uintptr_t base_addr);
@@ -19,4 +20,7 @@
 
 void __dead2 imx_system_off(void);
 void __dead2 imx_system_reset(void);
+int imx_validate_power_state(unsigned int power_state,
+			psci_power_state_t *req_state);
+void imx_get_sys_suspend_power_state(psci_power_state_t *req_state);
 #endif /*__PLAT_IMX8_H__ */