firmware: imx: make sure MU irq can wake up system from suspend mode

IRQF_NO_SUSPEND flag is set for MU IRQ of IPC work, but with this
flag set, IRQD_WAKEUP_ARMED flag will NOT be set during
suspend_device_irq() phase, then when MU IRQ arrives, it will NOT
wake up system from suspend.

To fix this issue, pm_system_wakeup() is called in general MU IRQ
handler to make sure system can be waked up when MU IRQ arrives.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

drivers/firmware/imx/imx-scu-irq.c

@@ -10,6 +10,7 @@
 #include <linux/firmware/imx/ipc.h>
 #include <linux/firmware/imx/sci.h>
 #include <linux/mailbox_client.h>
+#include <linux/suspend.h>
 
 #define IMX_SC_IRQ_FUNC_ENABLE	1
 #define IMX_SC_IRQ_FUNC_STATUS	2
@@ -91,6 +92,7 @@ static void imx_scu_irq_work_handler(struct work_struct *work)
 		if (!irq_status)
 			continue;
 
+		pm_system_wakeup();
 		imx_scu_irq_notifier_call_chain(irq_status, &i);
 	}
 }