perf record: Fix suggestion to get list of registers usable with --user-regs and --intr-regs

  $ perf record -h -I

   Usage: perf record [<options>] [<command>]
      or: perf record [<options>] -- <command> [<options>]

      -I, --intr-regs[=<any register>]
                            sample selected machine registers on interrupt, use -I ? to list register names

  $ m
  $ perf record -I ?
  Workload failed: No such file or directory
  $

  After:

  $ perf record -h -I

   Usage: perf record [<options>] [<command>]
      or: perf record [<options>] -- <command> [<options>]

      -I, --intr-regs[=<any register>]
                            sample selected machine registers on interrupt, use '-I?' to list register names

  $
  $ perf record -I?
  available registers: AX BX CX DX SI DI BP SP IP FLAGS CS SS R8 R9 R10 R11 R12 R13 R14 R15

   Usage: perf record [<options>] [<command>]
      or: perf record [<options>] -- <command> [<options>]

      -I, --intr-regs[=<any register>]
                            sample selected machine registers on interrupt, use '-I?' to list register names
  $

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Fixes: bcc84ec6 ("perf record: Add ability to name registers to record")
Link: https://lkml.kernel.org/n/tip-r0xhfhy5radmkhhcbcfs5izf@git.kernel.org


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