dt-bindings: usb: add binding for USB GPIO based connection detection driver

It's used to support dual role switch via GPIO when use Type-B
receptacle, typically the USB ID pin is connected to an input
GPIO, and also used to enable/disable device when the USB Vbus
pin is connected to an input GPIO.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1567070558-29417-4-git-send-email-chunfeng.yun@mediatek.com


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