coresight: etm4x: splitting etmv4 default configuration

Splitting and updating the default initialisation for each etmv4
configuration so that it can be called at the beginning of each
session rather than initialisation time only.

Since the trace ID isn't expected to change with every session,
moving it with the default tracer initialisation.

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