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: 54e3d9b5 ("watchdog: Add support for Armada 37xx CPU watchdog")
Reported-by: Hacash Robot <hacashRobot@santino.com>
Signed-off-by: William Dean <williamsukatube@gmail.com>
Reviewed-by: Marek Beh=C3=BAn <kabel@kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220722030938.2925156-1-williamsukatube@163.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>