drivers, pch_dma: Fix uninitialized var before use

In the function pdc_desc_get(), var 'i' is not
initialized before use. This patch fixes it.
Signed-off-by: Liu Yuan <tailai.ly@taobao.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/pch_dma.c

@@ -403,7 +403,7 @@ static struct pch_dma_desc *pdc_desc_get(struct pch_dma_chan *pd_chan)
 {
 	struct pch_dma_desc *desc, *_d;
 	struct pch_dma_desc *ret = NULL;
-	int i;
+	int i = 0;
 
 	spin_lock(&pd_chan->lock);
 	list_for_each_entry_safe(desc, _d, &pd_chan->free_list, desc_node) {