net/smc: prepare for more proposed ISM devices

SMCD Version 2 allows proposing of up to 8 ISM devices in addition
to the native ISM device of SMCD Version 1.
This patch prepares the struct smc_init_info to deal with these
additional 8 ISM devices.

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>