perf x86/topdown: Refine helper arch_is_topdown_metrics()

perf x86/topdown: Refine helper arch_is_topdown_metrics()

Leverage the existed function perf_pmu__name_from_config() to check if
an event is topdown metrics event. perf_pmu__name_from_config() goes
through the defined formats and figures out the config of pre-defined
topdown events.

This avoids to figure out the config of topdown pre-defined events with
hard-coded format strings "event=" and "umask=" and provides more
flexibility.

Suggested-by: Ian Rogers <irogers@google.com>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20241011110207.1032235-2-dapeng1.mi@linux.intel.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>