x86: vmxfeatures: rename features for consistency with KVM and manual

Three of the feature bits in vmxfeatures.h have names that are different
from the Intel SDM.  The names have been adjusted recently in KVM but they
were using the old name in the tip tree's x86/cpu branch.  Adjust for
consistency.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>