net/smc: add pnetid support for SMC-D and ISM

SMC-D relies on PNETIDs to find usable SMC-D/ISM devices for a SMC
connection. This patch adds SMC-D/ISM support to the current PNETID
implementation.

Signed-off-by: Hans Wippel <hwippel@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Suggested-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>