net/smc: add v2 support to the work request layer

net/smc: add v2 support to the work request layer

BugLink: https://bugs.launchpad.net/bugs/1929035
In the work request layer define one large v2 buffer for each link group
that is used to transmit and receive large LLC control messages.
Add the completion queue handling for this buffer.

Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 8799e310fb3f15759824a78b6b93d7e6d5def067)
Signed-off-by: Frank Heimes <frank.heimes@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>