Add binding documentation for Mediatek SoC SYSIRQ.
Signed-off-by: NYingjoe Chen <yingjoe.chen@mediatek.com>
Link: https://lkml.kernel.org/r/1416902662-19281-5-git-send-email-yingjoe.chen@mediatek.comSigned-off-by: NJason Cooper <jason@lakedaemon.net>