Documentation: coresight: Add cc_threshold tunable

This updates config option to include 'cc_threshold' tunable value.

Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: James Clark <james.clark@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230921033631.1298723-4-anshuman.khandual@arm.com

Documentation/trace/coresight/coresight.rst

@@ -624,6 +624,10 @@ They are also listed in the folder /sys/bus/event_source/devices/cs_etm/format/
    * - timestamp
      - Session local version of the system wide setting: :ref:`ETMv4_MODE_TIMESTAMP
        <coresight-timestamp>`
+   * - cc_threshold
+     - Cycle count threshold value. If nothing is provided here or the provided value is 0, then the
+       default value i.e 0x100 will be used. If provided value is less than minimum cycles threshold
+       value, as indicated via TRCIDR3.CCITMIN, then the minimum value will be used instead.
 
 How to use the STM module
 -------------------------