x86, cpu: Update AMD CPUID feature bits

AMD's public CPUID specification has been updated and some bits have
got names. Add them to properly describe new CPU features.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
LKML-Reference: <1283778860-26843-3-git-send-email-andre.przywara@amd.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>