dmaengine: idxd: remove set but not used variable 'idxd_cdev'

drivers/dma/idxd/cdev.c: In function idxd_cdev_open:
drivers/dma/idxd/cdev.c:77:20: warning:
variable idxd_cdev set but not used [-Wunused-but-set-variable]

commit 42d279f9137a ("dmaengine: idxd: add char driver to
expose submission portal to userland") involed this.

Reported-by: Hulk Robot <[e-mail]>
Signed-off-by: YueHaibing <[e-mail]>
Acked-by: Dave Jiang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/idxd/cdev.c

···
 	struct idxd_device *idxd;
 	struct idxd_wq *wq;
 	struct device *dev;
-	struct idxd_cdev *idxd_cdev;
 
 	wq = inode_wq(inode);
 	idxd = wq->idxd;
 	dev = &idxd->pdev->dev;
-	idxd_cdev = &wq->idxd_cdev;
 
 	dev_dbg(dev, "%s called\n", __func__);