perf cs-etm: Fix wrong return values in error path

Function cs_etm__mem_access() is supposed to return a u32 but the error
path returns negative values at a couple of places, something that really
throws off the clients using it.  Fix the situation by return '0'.
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki K Poulouse <suzuki.poulose@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20190212171618.25355-4-mathieu.poirier@linaro.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/cs-etm.c

@@ -324,7 +324,7 @@ static u32 cs_etm__mem_access(struct cs_etm_queue *etmq, u64 address,
 	struct	 addr_location al;
 
 	if (!etmq)
-		return -1;
+		return 0;
 
 	machine = etmq->etm->machine;
 	cpumode = cs_etm__cpu_mode(etmq, address);
@@ -332,7 +332,7 @@ static u32 cs_etm__mem_access(struct cs_etm_queue *etmq, u64 address,
 	thread = etmq->thread;
 	if (!thread) {
 		if (cpumode != PERF_RECORD_MISC_KERNEL)
-			return -EINVAL;
+			return 0;
 		thread = etmq->etm->unknown_thread;
 	}