rtc: da9063: simplify irq management

The code for enabling and disabling the irq is so similar that it can
easily be handled by one function. Like in most other RTC drivers. Save
the duplicated code and one layer of indirection.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20250320102218.10781-2-wsa+renesas@sang-engineering.com


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