coresight: etm3x: set progbit to stop trace collection

There is no need to use the event enable's "always false" event to
stop trace collection.  For that purpose setting the programming bit
(ETMCR:10) is enough.

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