perf intel-pt: Rationalize intel_pt_sync_switch()'s use of next_tid

Returning 1 from intel_pt_sync_switch() causes the current tid to be
set. That negates the need to keep next_tid anymore. Rationalize the
code to that effect.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20190412113830.4126-9-adrian.hunter@intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/intel-pt.c

@@ -1859,7 +1859,6 @@ static int intel_pt_sync_switch(struct intel_pt *pt, int cpu, pid_t tid,
 
 	switch (ptq->switch_state) {
 	case INTEL_PT_SS_NOT_TRACING:
-		ptq->next_tid = -1;
 		break;
 	case INTEL_PT_SS_UNKNOWN:
 	case INTEL_PT_SS_TRACING:
@@ -1879,13 +1878,14 @@ static int intel_pt_sync_switch(struct intel_pt *pt, int cpu, pid_t tid,
 		ptq->switch_state = INTEL_PT_SS_TRACING;
 		break;
 	case INTEL_PT_SS_EXPECTING_SWITCH_IP:
-		ptq->next_tid = tid;
 		intel_pt_log("ERROR: cpu %d expecting switch ip\n", cpu);
 		break;
 	default:
 		break;
 	}
 
+	ptq->next_tid = -1;
+
 	return 1;
 }