watchdog: imx2_wdt: set watchdog parent device

If on watchdog device registration a parent device is not set, then
the registered watchdog is considered to be a virtual device:

/sys/devices/virtual/watchdog/watchdog0
/sys/devices/virtual/watchdog/watchdog1

Setting a correct reference to a platform device allows to
distinguish multiple instances of iMX2+ hardware watchdogs:

/sys/devices/soc0/soc/2000000.aips-bus/20bc000.wdog/watchdog/watchdog0
/sys/devices/soc0/soc/2000000.aips-bus/20c0000.wdog/watchdog/watchdog1

Signed-off-by: Vladimir Zapolskiy <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/imx2_wdt.c

···
 	wdog->ops		= &imx2_wdt_ops;
 	wdog->min_timeout	= 1;
 	wdog->max_timeout	= IMX2_WDT_MAX_TIME;
+	wdog->parent		= &pdev->dev;
 
 	clk_prepare_enable(wdev->clk);