rtc: at91rm9200: double locking bug in at91_rtc_interrupt()

There is a typo here so we deadlock.

Fixes: dd1f1f39 ('rtc: at91rm9200: rework wakeup and interrupt handling')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Reported-by: David Dueck <davidcdueck@googlemail.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>