coresight: etm4x: split default and filter configuration

Splitting the steps involved in the configuration of a tracer.
The first part is generic and can be reused for both sysFS and
Perf methods.

The second part pertains to the configuration of filters
themselves where the source of the information used to
configure the filters will vary depending on the access
methods.

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