i2c: sh_mobile: avoid unused ret variable

Fix smatch warning:
drivers/i2c/busses/i2c-sh_mobile.c:564 \
  sh_mobile_i2c_request_dma_chan() warn: unused return: ret = PTR_ERR()

Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-sh_mobile.c

@@ -561,8 +561,8 @@ static struct dma_chan *sh_mobile_i2c_request_dma_chan(struct device *dev,
 
 	chan = dma_request_slave_channel_reason(dev, chan_name);
 	if (IS_ERR(chan)) {
-		ret = PTR_ERR(chan);
-		dev_dbg(dev, "request_channel failed for %s (%d)\n", chan_name, ret);
+		dev_dbg(dev, "request_channel failed for %s (%ld)\n", chan_name,
+			PTR_ERR(chan));
 		return chan;
 	}