[SCSI] mvsas: remove unused variable in mvs_task_exec()

We don't use "dev" any more after 07ec747a5f ("libsas: remove
ata_port.lock management duties from lldds") and it causes a compile
warning.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Xiangliang Yu <yuxiangl@marvell.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/mvsas/mv_sas.c

@@ -885,7 +885,6 @@ static int mvs_task_exec(struct sas_task *task, const int num, gfp_t gfp_flags,
 				struct completion *completion, int is_tmf,
 				struct mvs_tmf_task *tmf)
 {
-	struct domain_device *dev = task->dev;
 	struct mvs_info *mvi = NULL;
 	u32 rc = 0;
 	u32 pass = 0;