perf dwarf-aux: Fix __die_find_scope_cb() for namespaces

perf dwarf-aux: Fix __die_find_scope_cb() for namespaces

Currently __die_find_scope_cb() goes to check siblings when the DIE
doesn't include the given PC.

However namespaces don't have a PC and could contain children that have
that PC.

When we encounter a namespace, we should check both its children and
siblings.

Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Zecheng Li <zecheng@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Xu Liu <xliuprof@google.com>
Link: https://lore.kernel.org/r/20250825195817.226560-1-zecheng@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>