powerpc: Fix P10 PVR revision in /proc/cpuinfo for SMT4 cores

powerpc: Fix P10 PVR revision in /proc/cpuinfo for SMT4 cores

commit 030a2c689fb46e1690f7ded8b194bab7678efb28 upstream.

On POWER10 bit 12 in the PVR indicates if the core is SMT4 or SMT8.
Bit 12 is set for SMT4.

Without this patch, /proc/cpuinfo on a SMT4 DD1 POWER10 looks like
this:
  cpu             : POWER10, altivec supported
  revision        : 17.0 (pvr 0080 1100)

Fixes: a3ea40d5c736 ("powerpc: Add POWER10 architected mode")
Cc: stable@vger.kernel.org # v5.8
Signed-off-by: Michael Neuling <mikey@neuling.org>
Reviewed-by: Vaidyanathan Srinivasan <svaidy@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200803035600.1820371-1-mikey@neuling.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>