watchdog: armada_37xx_wdt: check the return value of devm_ioremap() in armada_37xx_wdt_probe()

The function devm_ioremap() in armada_37xx_wdt_probe() can fail, so
its return value should be checked.

Fixes: 54e3d9b518c8a ("watchdog: Add support for Armada 37xx CPU watchdog")
Reported-by: Hacash Robot <[e-mail]>
Signed-off-by: William Dean <[e-mail]>
Reviewed-by: Marek Beh=C3=BAn <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/armada_37xx_wdt.c

···
 	if (!res)
 		return -ENODEV;
 	dev->reg = devm_ioremap(&pdev->dev, res->start, resource_size(res));
+	if (!dev->reg)
+		return -ENOMEM;
 
 	/* init clock */
 	dev->clk = devm_clk_get(&pdev->dev, NULL);