perf/x86/intel/rapl: Fix pmus free during cleanup

On rapl cleanup path, kfree() is given by mistake the address of the
pointer of the structure to free (rapl_pmus->pmus + i). Pass the pointer
instead (rapl_pmus->pmus[i]).

Fixes: 9de8d686

 "perf/x86/intel/rapl: Convert it to a per package facility"
Signed-off-by: Vincent Stehlé <vincent.stehle@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1464101629-14905-1-git-send-email-vincent.stehle@intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>