perf annotate: Fix warning message on a missing vmlinux

perf annotate: Fix warning message on a missing vmlinux

When perf annotate runs with no vmlinux file it cannot annotate kernel
symbols because the kallsyms only provides symbol addresses.  So it
recommends to run perf buildid-cache to install proper vmlinux image.

But running perf buildid-cache -av vmlinux as the message gives me a
following error:

  $ perf buildid-cache -av /home/namhyung/build/kernel/vmlinux
  Couldn't add v: No such file or directory

Since the -a option receives a parameter, 'v' should not be after the
option.

In addition -a option is not work for this case since the build-id cache
already has a kallsyms with same build-id so it'll fail with EEXIST.
Use recently added -u (--update) option for it.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1360227734-375-6-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>