dmaengine: idxd: Fix warning for deadcode.deadstore

dmaengine: idxd: Fix warning for deadcode.deadstore

Deletes the  second initialization as the value stored to 'dev' during
its initialization (struct device *dev = &idxd->pdev->dev;) is
sufficient.

../drivers/dma/idxd/init.c:988:17: warning: Value stored to 'dev' during
its initialization is never read [deadcode.DeadStores]
  988 |         struct device *dev = &idxd->pdev->dev;
      |                        ^~~   ~~~~~~~~~~~~~~~~

Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/20250521231331.889204-1-anil.s.keshavamurthy@intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>