perf trace: Remove arg_fmt->is_enum, we can get that from the BTF type

perf trace: Remove arg_fmt->is_enum, we can get that from the BTF type

This is to pave the way for other BTF types, i.e. we try to find BTF
type then use things like btf_is_enum(btf_type) that we cached to find
the right strtoul and scnprintf routines.

For now only enum is supported, all the other types simple return zero
for scnprintf which makes it have the same behaviour as when BTF isn't
available, i.e. fallback to no pretty printing. Ditto for strtoul.

  root@x1:~# perf test -v enum
  124: perf trace enum augmentation tests                              : Ok
  root@x1:~# perf test -v enum
  124: perf trace enum augmentation tests                              : Ok
  root@x1:~# perf test -v enum
  124: perf trace enum augmentation tests                              : Ok
  root@x1:~# perf test -v enum
  124: perf trace enum augmentation tests                              : Ok
  root@x1:~# perf test -v enum
  124: perf trace enum augmentation tests                              : Ok
  root@x1:~#

Signed-off-by: Howard Chu <howardchu95@gmail.com>
Tested-by: Howard Chu <howardchu95@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Howard Chu <howardchu95@gmail.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240624181345.124764-9-howardchu95@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>