qeth: add support for af_iucv HiperSockets transport

This patch extends the HiperSockets device driver to send and receive
af_iucv traffic over HiperSockets transport.
TX: Driver uses new asynchronous delivery of storage blocks to pass
    flow control/congestion information from the HiperSockets microcode
    to the af_iucv socket.
RX: Memory for incoming traffic is preallocated and passed to
    HiperSockets layer. If receiver is not capable to clean its buffers
    shared with HiperSockets and pass new memory to the HiperSockets
    layer this will cause flow control/congestion events on the
    sender.

Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: Einar Lueck <elelueck@de.ibm.com>
Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>