net/smc: reduce amount of status updates to peer

In smc_cdc_msg_recv_action() the received cdc message is evaluated.
To reduce the number of messaged triggered by this evaluation the logic
is streamlined. For the write_blocked condition we do not need to send
a response immediately. The remaining conditions can be put together
into one if clause.

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