RDS: IB: mark rds_ib_fmr_wq static

Fix below warning by marking rds_ib_fmr_wq static

net/rds/ib_rdma.c:87:25: warning: symbol 'rds_ib_fmr_wq' was not declared. Should it be static?
Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>

net/rds/ib_rdma.c

@@ -83,7 +83,7 @@ struct rds_ib_mr_pool {
 	struct ib_fmr_attr	fmr_attr;
 };
 
-struct workqueue_struct *rds_ib_fmr_wq;
+static struct workqueue_struct *rds_ib_fmr_wq;
 
 int rds_ib_fmr_init(void)
 {