dmaengine: Remove redundant initialization of variable err

The variable err is being initialized with a value that is never read, it
is being updated later on. The assignment is redundant and can be removed
and move the declaration into the local scope.

Addresses-Coverity: ("Unused value")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20211015123447.27560-1-colin.king@canonical.comSigned-off-by: NVinod Koul <vkoul@kernel.org>

drivers/dma/dmaengine.c

@@ -695,13 +695,12 @@ static struct dma_chan *find_candidate(struct dma_device *device,
  */
 struct dma_chan *dma_get_slave_channel(struct dma_chan *chan)
 {
-	int err = -EBUSY;
-
 	/* lock against __dma_request_channel */
 	mutex_lock(&dma_list_mutex);
 
 	if (chan->client_count == 0) {
 		struct dma_device *device = chan->device;
+		int err;
 
 		dma_cap_set(DMA_PRIVATE, device->cap_mask);
 		device->privatecnt++;