watchdog: imgpdc: Fix probe NULL pointer dereference

The IMG PDC watchdog probe function calls pdc_wdt_stop() prior to
watchdog_set_drvdata(), causing a NULL pointer dereference when
pdc_wdt_stop() retrieves the struct pdc_wdt_dev pointer using
watchdog_get_drvdata() and reads the register base address through it.

Fix by moving the watchdog_set_drvdata() call earlier, to where various
other pdc_wdt->wdt_dev fields are initialised.

Fixes: 93937669e9b5 ("watchdog: ImgTec PDC Watchdog Timer Driver")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Ezequiel Garcia <ezequiel.garcia@imgtec.com>
Cc: Naidu Tellapati <Naidu.Tellapati@imgtec.com>
Cc: Jude Abraham <Jude.Abraham@imgtec.com>
Cc: linux-watchdog@vger.kernel.org
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/imgpdc_wdt.c

@@ -191,6 +191,7 @@ static int pdc_wdt_probe(struct platform_device *pdev)
 	pdc_wdt->wdt_dev.ops = &pdc_wdt_ops;
 	pdc_wdt->wdt_dev.max_timeout = 1 << PDC_WDT_CONFIG_DELAY_MASK;
 	pdc_wdt->wdt_dev.parent = &pdev->dev;
+	watchdog_set_drvdata(&pdc_wdt->wdt_dev, pdc_wdt);
 
 	ret = watchdog_init_timeout(&pdc_wdt->wdt_dev, heartbeat, &pdev->dev);
 	if (ret < 0) {
@@ -232,7 +233,6 @@ static int pdc_wdt_probe(struct platform_device *pdev)
 	watchdog_set_nowayout(&pdc_wdt->wdt_dev, nowayout);
 
 	platform_set_drvdata(pdev, pdc_wdt);
-	watchdog_set_drvdata(&pdc_wdt->wdt_dev, pdc_wdt);
 
 	ret = watchdog_register_device(&pdc_wdt->wdt_dev);
 	if (ret)