perf/x86/intel/uncore: Fix wrong box pointer check

perf/x86/intel/uncore: Fix wrong box pointer check

commit 80c65fdb4c6920e332a9781a3de5877594b07522 upstream.

Should not init a NULL box. It will cause system crash.
The issue looks like caused by a typo.

This was not noticed because there is no NULL box. Also, for most
boxes, they are enabled by default. The init code is not critical.

Fixes: fff4b87e594a ("perf/x86/intel/uncore: Make package handling more robust")
Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170629190926.2456-1-kan.liang@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>