coresight-etm4x: Controls pertaining to various configuration options

Adding sysfs entries to configure:
. global timestamp.
. how often trace synchronisation occur.
. the threashold value for cycle counting.
. branch and broadcasting regions.

Signed-off-by: Pratik Patel <pratikp@codeaurora.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>