perf unwind: Suppress massive unsupported target platform errors

When cross-analyzing perf data recorded on an another platform, massive
unsupported target platform errors are printed. So let's show this message
as warning and only once.

Signed-off-by: Changbin Du <changbin.du@huawei.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Hui Wang <hw.huiwang@huawei.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.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/20230426032246.3608596-1-changbin.du@huawei.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>