rtc: isl1208: Add "evdet" interrupt source for isl1219

Add support for "evdet" named interrupt source.

The check if i2c client irq matches evdet irq is needed
for the case that there is only one interrupt named "evdet".
In this case i2c client code handles this like an unnamed
interrupt souce and assigns the value.

Signed-off-by: Denis Osterland <Denis.Osterland@diehl.com>
Reviewed-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>