rtc: pm8xxx: switch to devm_device_init_wakeup

Switch to devm_device_init_wakeup to avoid a possible memory leak as wakeup
is never disabled.

Link: https://lore.kernel.org/r/20250303223600.1135142-3-alexandre.belloni@bootlin.com


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>