mtd: nand: sh_flctl: handle dma_submit() errors

Some build tools noticed that 'cookie' is being set but not used. Might
as well catch the errors here and handle them the same way we handle
other DMA prep steps.

Signed-off-by: Brian Norris <[e-mail]>
Signed-off-by: Boris Brezillon <[e-mail]>

drivers/mtd/nand/sh_flctl.c

···
 	struct dma_chan *chan;
 	enum dma_transfer_direction tr_dir;
 	dma_addr_t dma_addr;
-	dma_cookie_t cookie = -EINVAL;
+	dma_cookie_t cookie;
 	uint32_t reg;
 	int ret;
 
···
 		desc->callback = flctl_dma_complete;
 		desc->callback_param = flctl;
 		cookie = dmaengine_submit(desc);
+		if (dma_submit_error(cookie)) {
+			ret = dma_submit_error(cookie);
+			dev_warn(&flctl->pdev->dev,
+				 "DMA submit failed, falling back to PIO\n");
+			goto out;
+		}
 
 		dma_async_issue_pending(chan);
 	} else {