perf/x86: Fix typo in uncore_pmu_to_box

The variable box should not be declared as static.

This could probably cause crashes with sufficiently parallel
uncore PMU use.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Cc: eranian@google.com
Cc: a.p.zijlstra@chello.nl
Link: http://lkml.kernel.org/r/1348709606-2759-1-git-send-email-zheng.z.yan@intel.com


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