perf lock: Dropping unsupported ':r' modifier

Looks to me like the :r modifier is not supported anymore, so remove it
from the list of events. Without this fix 'perf lock record' doesn't
work.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Zhu Yanhai <gaoyang.zyh@taobao.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1312035232-9534-1-git-send-email-gaoyang.zyh@taobao.com
Signed-off-by: Zhu Yanhai <gaoyang.zyh@taobao.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>