scsi: sd: Remove obsolete variable in sd_remove()

Commit 996e509b ("sd: use __register_blkdev to avoid a modprobe for an
unregistered dev_t") removed blk_register_region(devt, ...) in sd_remove()
and since then, devt is unused in sd_remove().

Hence, make W=1 warns:

  drivers/scsi/sd.c:3516:8:
      warning: variable 'devt' set but not used [-Wunused-but-set-variable]

Simply remove this obsolete variable.

[mkp: fixed commit sha]

Link: https://lore.kernel.org/r/20201214095424.12479-1-lukas.bulwahn@gmail.comReviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/sd.c

@@ -3512,10 +3512,8 @@ static int sd_probe(struct device *dev)
 static int sd_remove(struct device *dev)
 {
 	struct scsi_disk *sdkp;
-	dev_t devt;
 
 	sdkp = dev_get_drvdata(dev);
-	devt = disk_devt(sdkp->disk);
 	scsi_autopm_get_device(sdkp->device);
 
 	async_synchronize_full_domain(&scsi_sd_pm_domain);