rtc: rx8025: protect ctrl1 register update by rtc->ops_lock

The ctrl1 register is accessed by alarm operations.  But it is updated
in threaded interrupt handler without acquiring rtc->ops_lock.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>