perf events, x86, P4: Fix typo in comment

Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
Acked-by: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: trivial@kernel.org
Link: http://lkml.kernel.org/r/1303492132-3004-1-git-send-email-justinmattock@gmail.com


Signed-off-by: Ingo Molnar <mingo@elte.hu>