rng: remove the unused request cancellation code rng_backend_cancel_requests had no callers and none of the code deleted in this commit ever ran. Signed-off-by: Ladi Prosek <lprosek@redhat.com> Reviewed-by: Amit Shah <amit.shah@redhat.com> Message-Id: <1456994238-9585-2-git-send-email-lprosek@redhat.com> Signed-off-by: Amit Shah <amit.shah@redhat.com>