Fixes the following sparse warning:

drivers/irqchip/irq-jcore-aic.c:47:12: warning:
 symbol 'aic_irq_of_init' was not declared. Should it be static?
Signed-off-by: NWei Yongjun <weiyj.lk@gmail.com>
Link: https://lkml.kernel.org/r/1471706788-27587-1-git-send-email-weiyj.lk@gmail.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>