perf cs-etm: Fix the assert() to handle captured and unprocessed cpu trace

If one builds perf with DEBUG=1, captures data on multiple CPUs and
finally runs 'perf report -C <cpu>' for only one of the cpus, assert()
aborts the program. This happens because there are empty queues with
format set.

This patch changes the condition to abort only if a queue is not empty
and if the format is unset.

$ make -C tools/perf DEBUG=1 CORESIGHT=1 CSLIBS=/usr/lib CSINCLUDES=/usr/include install
$ perf record -o kcore --kcore -e cs_etm/timestamp/k -s -C 0-1 dd if=/dev/zero of=/dev/null bs=1M count=1
$ perf report --input kcore/data --vmlinux=/home/ikoskine/projects/linux/vmlinux -C 1
Aborted (core dumped)

Fixes: 57880a7966be510c ("perf: cs-etm: Allocate queues for all CPUs")
Reviewed-by: James Clark <[e-mail]>
Signed-off-by: Ilkka Koskinen <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: James Clark <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: John Garry <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Leo Yan <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Mike Leach <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Suzuki Poulouse <[e-mail]>
Cc: Will Deacon <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/cs-etm.c

···
 		 * Don't create decoders for empty queues, mainly because
 		 * etmq->format is unknown for empty queues.
 		 */
-		assert(empty == (etmq->format == UNSET));
+		assert(empty || etmq->format != UNSET);
 		if (empty)
 			continue;