Add device tree bindings document for reboot-mode driver.
Signed-off-by: NAndy Yan <andy.yan@rock-chips.com>
Acked-by: NRob Herring <robh@kernel.org>
Reviewed-by: NKrzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: NSebastian Reichel <sre@kernel.org>