coresight: Use event attributes for sink selection

This patch uses the information conveyed by perf_event::attr::config2
to select a sink to use for the session.  That way a sink can easily be
selected to be used by more than one source, something that isn't currently
possible with the sysfs implementation.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>