scsi: mvsas: Remove set but not used variable 'id'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/scsi/mvsas/mv_sas.c: In function 'mvs_work_queue':
drivers/scsi/mvsas/mv_sas.c:1909:31: warning:
 variable 'id' set but not used [-Wunused-but-set-variable]

It never used since introduction in commit
20b09c2992 ("[SCSI] mvsas: add support for 94xx; layout change; bug fixes")

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/mvsas/mv_sas.c

@@ -1905,8 +1905,7 @@ static void mvs_work_queue(struct work_struct *work)
 
 		if (phy->phy_event & PHY_PLUG_OUT) {
 			u32 tmp;
-			struct sas_identify_frame *id;
-			id = (struct sas_identify_frame *)phy->frame_rcvd;
+
 			tmp = MVS_CHIP_DISP->read_phy_ctl(mvi, phy_no);
 			phy->phy_event &= ~PHY_PLUG_OUT;
 			if (!(tmp & PHY_READY_MASK)) {