Coresight: Use coresight_etm_get_trace_id() in traceid_show()

Use the new API, coresight_etm_get_trace_id, to read the traceid of the ETM
device when call traceid_show via sysfs node.

Signed-off-by: James Clark <james.clark@linaro.org>
Reviewed-by: James Clark <james.clark@linaro.org>
Signed-off-by: Jie Gan <quic_jiegan@quicinc.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250303032931.2500935-4-quic_jiegan@quicinc.com