rtc: pcf8563: Fix interrupt trigger method

rtc: pcf8563: Fix interrupt trigger method

BugLink: https://bugs.launchpad.net/bugs/1863019
[ Upstream commit 65f662cbf829834fa4d94190eb7691e5a9cb92d8 ]

The PCF8563 datasheet says the interrupt line is active low and stays
active until the events are cleared, i.e. a level trigger interrupt.

Fix the flags used to request the interrupt.

Fixes: ede3e9d47cca ("drivers/rtc/rtc-pcf8563.c: add alarm support")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>