watchdog: at91sam9_wdt: use devm_request_irq to avoid missing free_irq() in error path

free_irq() is missing in case of error in at91_wdt_init(), use
devm_request_irq to fix that.

Fixes: 5161b31d ("watchdog: at91sam9_wdt: better watchdog support")
Signed-off-by: ruanjinjie <ruanjinjie@huawei.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20221116094950.3141943-1-ruanjinjie@huawei.com


[groeck: Adjust multi-line alignment]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>