perf test parse-events: Use evsel__match for legacy events

perf test parse-events: Use evsel__match for legacy events

Switch from the test's assert_hw/test_config to the common
evsel__match code that appropriately handles events with both legacy
and sysfs/json encoding.

For tests asserting that a config value matches that placed in the
perf_event_attr just directly compare the config values.

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