isci: unify phy event handlers

Unify the implementations in scic_sds_phy_event_handler(), and kill the state handler
Reported-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

drivers/scsi/isci/phy.h

@@ -511,11 +511,6 @@ typedef enum sci_status (*scic_sds_phy_frame_handler_t)(struct scic_sds_phy *, u
 typedef enum sci_status (*scic_sds_phy_power_handler_t)(struct scic_sds_phy *);
 
 struct scic_sds_phy_state_handler {
-	/**
-	 * The state handler for events received from the SCU hardware.
-	 */
-	scic_sds_phy_event_handler_t event_handler;
-
 	/**
 	 * The state handler for staggered spinup.
 	 */