dma: imx-dma: fix imxdma_probe error path

otherwise, i will be -1 inside the latest iteration of the while loop.
Signed-off-by: NAxel Lin <axel.lin@gmail.com>
Acked-by: NSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

drivers/dma/imx-dma.c

@@ -379,7 +379,7 @@ static int __init imxdma_probe(struct platform_device *pdev)
 	return 0;
 
 err_init:
-	while (i-- >= 0) {
+	while (--i >= 0) {
 		struct imxdma_channel *imxdmac = &imxdma->channel[i];
 		imx_dma_free(imxdmac->imxdma_channel);
 	}