perf inject: Rename perf_evsel__*() operating on 'struct evsel *' to evsel__*()

As those is a 'struct evsel' methods, not part of tools/lib/perf/, aka
libperf, to whom the perf_ prefix belongs.

Cc: Adrian Hunter <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/builtin-inject.c

···
 	session_done = 1;
 }
 
-static int perf_evsel__check_stype(struct evsel *evsel,
-				   u64 sample_type, const char *sample_msg)
+static int evsel__check_stype(struct evsel *evsel, u64 sample_type, const char *sample_msg)
 {
 	struct perf_event_attr *attr = &evsel->core.attr;
 	const char *name = evsel__name(evsel);
···
 			const char *name = evsel__name(evsel);
 
 			if (!strcmp(name, "sched:sched_switch")) {
-				if (perf_evsel__check_stype(evsel, PERF_SAMPLE_TID, "TID"))
+				if (evsel__check_stype(evsel, PERF_SAMPLE_TID, "TID"))
 					return -EINVAL;
 
 				evsel->handler = perf_inject__sched_switch;