IB/hfi1: Fix "suspicious rcu_dereference_check() usage" warnings

This fixes the following warnings with PROVE_LOCKING and PROVE_RCU
enabled in the kernel:

case (1):
[ INFO: suspicious RCU usage. ]
drivers/infiniband/hw/hfi1/init.c:532
suspicious rcu_dereference_check() usage!

case (2):
[ INFO: suspicious RCU usage. ]
drivers/infiniband/hw/hfi1/hfi.h:1624
suspicious rcu_dereference_check() usage!

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Jianxin Xiong <jianxin.xiong@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>