perf trace: Associate the "msr" tracepoint arg name with x86_MSR__scnprintf()

So that we can go from:

  # perf trace -e msr:write_msr --max-stack=16 sleep 1
       0.000 sleep/6740 msr:write_msr(msr: 3221225728, val: 139636317451648)
                                         do_trace_write_msr ([kernel.kallsyms])
                                         do_trace_write_msr ([kernel.kallsyms])
                                         do_arch_prctl_64 ([kernel.kallsyms])
                                         __x64_sys_arch_prctl ([kernel.kallsyms])
                                         do_syscall_64 ([kernel.kallsyms])
                                         entry_SYSCALL_64 ([kernel.kallsyms])
                                         init_tls (/usr/lib64/ld-2.29.so)
                                         dl_main (/usr/lib64/ld-2.29.so)
                                         _dl_sysdep_start (/usr/lib64/ld-2.29.so)
                                         _dl_start (/usr/lib64/ld-2.29.so)
  #

To:

  # perf trace -e msr:write_msr --max-stack=16 sleep 1
     0.000 sleep/8519 msr:write_msr(msr: FS_BASE, val: 139878031705472)
                                       do_trace_write_msr ([kernel.kallsyms])
                                       do_trace_write_msr ([kernel.kallsyms])
                                       do_arch_prctl_64 ([kernel.kallsyms])
                                       __x64_sys_arch_prctl ([kernel.kallsyms])
                                       do_syscall_64 ([kernel.kallsyms])
                                       entry_SYSCALL_64 ([kernel.kallsyms])
                                       init_tls (/usr/lib64/ld-2.29.so)
                                       dl_main (/usr/lib64/ld-2.29.so)
                                       _dl_sysdep_start (/usr/lib64/ld-2.29.so)
                                       _dl_start (/usr/lib64/ld-2.29.so)
  #

This, in reverse, will allow for symbolic system call/tracepoint
filtering.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-q1q4unmqja5ex7dy0kb5cjaa@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-trace.c

@@ -1480,6 +1480,7 @@ static int syscall__alloc_arg_fmts(struct syscall *sc, int nr_args)
 }
 
 static struct syscall_arg_fmt syscall_arg_fmts__by_name[] = {
+	{ .name = "msr", .scnprintf = SCA_X86_MSR, }
 };
 
 static int syscall_arg_fmt__cmp(const void *name, const void *fmtp)