perf script: Always allow field 'data_src' for auxtrace

If use command 'perf script -F,+data_src' to dump memory samples with
Arm SPE trace data, it reports error:

  # perf script -F,+data_src
  Samples for 'dummy:u' event do not have DATA_SRC attribute set. Cannot print 'data_src' field.

This is because the 'dummy:u' event is absent DATA_SRC bit in its sample
type, so if a file contains AUX area tracing data then always allow
field 'data_src' to be selected as an option for perf script.

Fixes: e55ed342

 ("perf arm-spe: Synthesize memory event")
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: German Gomez <german.gomez@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220417114837.839896-1-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>