KVM: SVM: Enable Virtual VMLOAD VMSAVE feature

Enable the Virtual VMLOAD VMSAVE feature. This is done by setting bit 1
at position B8h in the vmcb.

The processor must have nested paging enabled, be in 64-bit mode and
have support for the Virtual VMLOAD VMSAVE feature for the bit to be set
in the vmcb.

Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>