net/smc: build and send V2 CLC proposal

The new format of an SMCD V2 CLC proposal is introduced, and
building and checking of SMCD V2 CLC proposals is adapted
accordingly.

Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>