isci: Remove obviated host callback list.

Since the callbacks to libsas now occur under scic_lock, there is no
longer any reason to save the completed requests in a separate list
for completion to libsas.

Signed-off-by: Jeff Skirvin <jeffrey.d.skirvin@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/scsi/isci/request.h

@@ -95,8 +95,6 @@ struct isci_request {
 		struct isci_tmf *tmf_task_ptr;  /* When ttype==tmf_task */
 	} ttype_ptr;
 	struct isci_host *isci_host;
-	/* For use in the requests_to_{complete|abort} lists: */
-	struct list_head completed_node;
 	dma_addr_t request_daddr;
 	dma_addr_t zero_scatter_daddr;
 	unsigned int num_sg_entries;