perf tests: Add tests of new pinned modifier

perf tests: Add tests of new pinned modifier

Add a negative test to test__checkevent_pmu_events() to get lots of
coverage of the negative case, ie. when the modifier is not specified.

Add a test of a single event, and of the group case.

Signed-off-by: Michael Ellerman <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>