clocksource/drivers/ingenic: Add support for TCU of X1000

X1000 has a different TCU containing OST, since X1000, OST has been
independent of TCU. This patch is prepare for later OST driver.

Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1582100974-129559-5-git-send-email-zhouyanjie@wanyeetech.com