xen/pt: Update comments with proper function name. It has changed but the comments still refer to the old names. Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>