watchdog: imx_sc: Add pretimeout support

i.MX system controller watchdog can support pretimeout IRQ
via general SCU MU IRQ, it depends on IMX_SCU and driver MUST
be probed after SCU IPC ready, then enable corresponding SCU
IRQ group and register SCU IRQ notifier, when watchdog pretimeout
IRQ fires, SCU MU IRQ will be handled and watchdog pretimeout
notifier will be called to handle the event.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index ffe7545..975e573 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -717,6 +717,7 @@
 config IMX_SC_WDT
 	tristate "IMX SC Watchdog"
 	depends on HAVE_ARM_SMCCC
+	depends on IMX_SCU
 	select WATCHDOG_CORE
 	help
 	  This is the driver for the system controller watchdog