dt-bindings: usb: mtk-xhci: add wakeup interrupt

Add an interrupt which is EINT usually to support runtime PM,
meanwhile add "interrupt-names" property, for backward
compatibility, it's optional and used when wakeup interrupt
exists

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1618031406-15347-2-git-send-email-chunfeng.yun@mediatek.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>