perf trace: Fix 'newfstatat'/'fstatat' argument pretty printing

perf trace: Fix 'newfstatat'/'fstatat' argument pretty printing

There were needless two entries, one for 'newfstatat' and another for
'fstatat', keep just one and pretty print its 'flags' argument using the
fs_at_flags scnprintf that is also used by other FS syscalls such as
'stat', now:

  root@number:~# perf trace -e newfstatat --max-events=5
       0.000 ( 0.010 ms): abrt-dump-jour/1400 newfstatat(dfd: 7, filename: "", statbuf: 0x7fff0d127000, flag: EMPTY_PATH) = 0
       0.020 ( 0.003 ms): abrt-dump-jour/1400 newfstatat(dfd: 9, filename: "", statbuf: 0x55752507b0e8, flag: EMPTY_PATH) = 0
       0.039 ( 0.004 ms): abrt-dump-jour/1400 newfstatat(dfd: 19, filename: "", statbuf: 0x557525061378, flag: EMPTY_PATH) = 0
       0.047 ( 0.003 ms): abrt-dump-jour/1400 newfstatat(dfd: 20, filename: "", statbuf: 0x5575250b8cc8, flag: EMPTY_PATH) = 0
       0.053 ( 0.003 ms): abrt-dump-jour/1400 newfstatat(dfd: 22, filename: "", statbuf: 0x5575250535d8, flag: EMPTY_PATH) = 0
  root@number:~#

Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/20240320193115.811899-6-acme@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>