isci: remove request task context completion state handler

Unlike the other conversions this only updates
scic_sds_io_request_tc_completion() to call the old state handlers directly
(with less verbose names).  This was done for future patch readability, the
implementations have only minor differences for different completion codes.
Without a reference to the function name it would be difficult to dicern which
state is being updated.  Considered changing the order to look up the
completion code before the state but that was not a clean conversion either.
Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/scsi/isci/request.h

@@ -426,8 +426,6 @@ typedef enum sci_status (*scic_sds_io_request_handler_t)
 				(struct scic_sds_request *request);
 typedef enum sci_status (*scic_sds_io_request_event_handler_t)
 				(struct scic_sds_request *req, u32 event);
-typedef enum sci_status (*scic_sds_io_request_task_completion_handler_t)
-				(struct scic_sds_request *req, u32 completion_code);
 
 /**
  * struct scic_sds_io_request_state_handler - This is the SDS core definition
@@ -442,7 +440,6 @@ struct scic_sds_io_request_state_handler {
 	 */
 	scic_sds_io_request_handler_t complete_handler;
 
-	scic_sds_io_request_task_completion_handler_t tc_completion_handler;
 	scic_sds_io_request_event_handler_t event_handler;
 };