Clock cs_atb_syspll is pll used for coresight trace bus; when clock
cs_atb_syspll is disabled and operates its child clock node cs_atb
results in system hang. So mark clock cs_atb_syspll as critical to
keep it enabled.

Cc: Guodong Xu <guodong.xu@linaro.org>
Cc: Zhangfei Gao <zhangfei.gao@linaro.org>
Cc: Haojian Zhuang <haojian.zhuang@linaro.org>
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>
Link: lkml.kernel.org/r/1504226835-2115-2-git-send-email-leo.yan@linaro.org