smc: switch to usage of IB_PD_UNSAFE_GLOBAL_RKEY

Currently, SMC enables remote access to physical memory when a user
has successfully configured and established an SMC-connection until ten
minutes after the last SMC connection is closed. Because this is considered
a security risk, drivers are supposed to use IB_PD_UNSAFE_GLOBAL_RKEY in
such a case.

This patch changes the current SMC code to use IB_PD_UNSAFE_GLOBAL_RKEY.
This improves user awareness, but does not remove the security risk itself.

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