RDS: make use of kfree_rcu() and avoid the call_rcu() chain

RDS: make use of kfree_rcu() and avoid the call_rcu() chain

call_rcu() chains are expensive and its use in rds_ib_remove_ipaddr()
is just to kfree() the rds_ib_ipaddr. Chains make use of  high-latency
rcu_barrier() in modules which can be avoided.

Makes use of kfree_rcu() which is exactly meant for such use

Orabug: 22010933

Acked-by: Ajaykumar Hotchandani <ajaykumar.hotchandani@oracle.com>
Acked-by: Wengang Wang <wen.gang.wang@oracle.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>