mtip32xx: convert internal commands to regular block infrastructure

Get rid of the private end_io handlers and data, and just use the
regular block IO path for these requests. This removes a lot of
redundant code.
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/block/mtip32xx/mtip32xx.h

@@ -333,16 +333,6 @@ struct mtip_cmd {
 
 	dma_addr_t command_dma; /* corresponding physical address */
 
-	void *comp_data; /* data passed to completion function comp_func() */
-	/*
-	 * Completion function called by the ISR upon completion of
-	 * a command.
-	 */
-	void (*comp_func)(struct mtip_port *port,
-				int tag,
-				struct mtip_cmd *cmd,
-				int status);
-
 	int scatter_ents; /* Number of scatter list entries used */
 
 	int unaligned; /* command is unaligned on 4k boundary */