perf test: Switch cycles event to cpu-cycles

perf test: Switch cycles event to cpu-cycles

Without a PMU perf matches an event against any PMU with the
event. Unfortunately some PMU drivers advertise a "cycles" event which
is typically just a core event. As tests assume a core event, switch
to use "cpu-cycles" that avoids the overloaded "cycles" event on
troublesome PMUs and is so far not overloaded. Note, on x86 this
changes a legacy event into a sysfs one.

Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: James Clark <james.clark@linaro.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>