print_svm_info: decode a CPUID 0x8000000a.edx bit 20.

This is SVM features word, the bit is defined in "PPR for AMD Family
17h Model 31h B0", document 55803 Rev 0.54.

N.B. GuesSpecCtl (no 't') is the spelling from the document.

Submitted by: Dmitry Luhtionov <dmitryluhtionov@gmail.com>
MFC after: 3 days