af_vsock: SOCK_SEQPACKET receive timeout test

Test for receive timeout check: connection is established,
receiver sets timeout, but sender does nothing. Receiver's
'read()' call must return EAGAIN.

Signed-off-by: Krasnov Arseniy Vladimirovich <AVKrasnov@sberdevices.ru>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>