perf list: Place the header text in its right position

The hearer text 'List of pre-defined events (to be used in -e):' is
placed in an improper function, which causes an abnormal output, e.g.
'perf list hw' shows no guiding text at all, and 'perf list hw
L1-dcache*' shows the guiding text incorrectly in the middle of the
output.

Example
Before this patch:

 $ perf list hw L1-dcache*

   branch-instructions OR branches                    [Hardware event]
   branch-misses                                      [Hardware event]
   bus-cycles                                         [Hardware event]
   cache-misses                                       [Hardware event]
   cache-references                                   [Hardware event]
   cpu-cycles OR cycles                               [Hardware event]
   instructions                                       [Hardware event]
   stalled-cycles-backend OR idle-cycles-backend      [Hardware event]
   stalled-cycles-frontend OR idle-cycles-frontend    [Hardware event]

 List of pre-defined events (to be used in -e):              <-- incorrect position
   L1-dcache-load-misses                              [Hardware cache event]
   L1-dcache-loads                                    [Hardware cache event]
   L1-dcache-prefetch-misses                          [Hardware cache event]
   L1-dcache-prefetches                               [Hardware cache event]
   L1-dcache-store-misses                             [Hardware cache event]
   L1-dcache-stores                                   [Hardware cache event]

After this patch:

 $ perf list hw L1-dcache*

 List of pre-defined events (to be used in -e):              <-- correct position

   branch-instructions OR branches                    [Hardware event]
   branch-misses                                      [Hardware event]
   bus-cycles                                         [Hardware event]
   cache-misses                                       [Hardware event]
   cache-references                                   [Hardware event]
   cpu-cycles OR cycles                               [Hardware event]
   instructions                                       [Hardware event]
   stalled-cycles-backend OR idle-cycles-backend      [Hardware event]
   stalled-cycles-frontend OR idle-cycles-frontend    [Hardware event]

   L1-dcache-load-misses                              [Hardware cache event]
   L1-dcache-loads                                    [Hardware cache event]
   L1-dcache-prefetch-misses                          [Hardware cache event]
   L1-dcache-prefetches                               [Hardware cache event]
   L1-dcache-store-misses                             [Hardware cache event]
   L1-dcache-stores                                   [Hardware cache event]

Signed-off-by: Yunlong Song <yunlong.song@huawei.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1423833115-11199-8-git-send-email-yunlong.song@huawei.com


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