MAINTAINERS: Add CoreSight mailing list

Add CoreSight mailing list so that people can participate in patch
reviews and know what features are coming next.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200916191737.4001561-13-mathieu.poirier@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>