SBOX on some Broadwell CPUs is broken because it's enabled unconditionally
despite the fact that there are no SBOXes available.

Check the Power Control Unit CAPID4 register to determine the number of
available SBOXes on the particular CPU before trying to enable them. If
there are none, nullify the SBOX descriptor so it isn't tried to be
initialized.
Signed-off-by: Oskar Senft <osk@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Mark van Dijk <mark@voidzero.net>
Reviewed-by: Kan Liang <kan.liang@intel.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: ak@linux.intel.com
Cc: peterz@infradead.org
Cc: eranian@google.com
Link: https://lkml.kernel.org/r/1521810690-2576-2-git-send-email-kan.liang@linux.intel.com