perf pmu: Push configuration down to PMU driver

This patch adds a PMU callback and the required mechanic so that drivers
can process the command line configuration elements found in
evsel::config_terms.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1474041004-13956-6-git-send-email-mathieu.poirier@linaro.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>