dt-bindings: timer: Add X1000 bindings.

Add the timer bindings for the X1000 Soc from Ingenic.

Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1582100974-129559-3-git-send-email-zhouyanjie@wanyeetech.com