KVM: x86: Expose Hyper-V L2 TLB flush feature

With both nSVM and nVMX implementations in place, KVM can now expose
Hyper-V L2 TLB flush feature to userspace.

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221101145426.251680-30-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>