rtc: ingenic: Fix masking of error code

The code was returning -ENOENT on any error of platform_get_irq(), even
if it returned a different error.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20200505221336.222313-6-paul@crapouillou.net


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