RDMA/i40iw: Do not set self-referencing pointer to NULL after free

iwqp->allocated_buffer is a self-referencing pointer to iwqp.
Do not set iwqp->allocated_buffer to NULL after freeing it.

Signed-off-by: Mustafa Ismail <mustafa.ismail@intel.com>
Signed-off-by: Faisal Latif <faisal.latif@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/i40iw/i40iw_verbs.c

@@ -437,7 +437,6 @@ void i40iw_free_qp_resources(struct i40iw_device *iwdev,
 	kfree(iwqp->kqp.wrid_mem);
 	iwqp->kqp.wrid_mem = NULL;
 	kfree(iwqp->allocated_buffer);
-	iwqp->allocated_buffer = NULL;
 }
 
 /**