net/smc: remove unnecessary cast

Remove an unneeded (void *) cast from the calls to
smc_llc_send_message(). No functional changes.

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>