linux-wandboard

MLK-16704-1: watchdog: imx8_wdt: add watchdog driver for i.mx8QM/QXP

This watchdog driver is a virtual driver in Linux and call ATF interface
where call SCFW eventually. In SCFW, it's done by SCU timer tick instead
of hardware watchdog.This is why we have to call ATF because such system
resource owned by secure patition.Currently, booard reset happen if not
ping this software watchdog in time in linux side, may change to partition
reboot once SCFW support this feature in the future.
 BuildInfo:
   - SCFW 93c142a9, IMX-MKIMAGE 2522fd70, ATF f2547fb
   - U-Boot 2017.03-00097-gd7599cf

Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Reviewed-by: Anson Huang <Anson.Huang@nxp.com>