perf/x86: Fix format definition of SNB-EP uncore QPI box

The event control register of SNB-EP uncore QPI box has a one bit
extension at bit position 21.

Reported-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1343097850-4348-1-git-send-email-zheng.z.yan@intel.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>