[media] cxusb: unlock on error in cxusb_i2c_xfer()

We recently introduced some new error paths which are missing their
unlocks.
Fixes: 64f7ef8afbf8 ('[media] cxusb: Don't use dynamic static allocation')

Signed-off-by: Dan Carpenter <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/usb/dvb-usb/cxusb.c

···
 			  int num)
 {
 	struct dvb_usb_device *d = i2c_get_adapdata(adap);
+	int ret;
 	int i;
 
 	if (mutex_lock_interruptible(&d->i2c_mutex) < 0)
···
 			if (1 + msg[i].len > sizeof(ibuf)) {
 				warn("i2c rd: len=%d is too big!\n",
 				     msg[i].len);
-				return -EOPNOTSUPP;
+				ret = -EOPNOTSUPP;
+				goto unlock;
 			}
 			obuf[0] = 0;
 			obuf[1] = msg[i].len;
···
 			if (3 + msg[i].len > sizeof(obuf)) {
 				warn("i2c wr: len=%d is too big!\n",
 				     msg[i].len);
-				return -EOPNOTSUPP;
+				ret = -EOPNOTSUPP;
+				goto unlock;
 			}
 			if (1 + msg[i + 1].len > sizeof(ibuf)) {
 				warn("i2c rd: len=%d is too big!\n",
 				     msg[i + 1].len);
-				return -EOPNOTSUPP;
+				ret = -EOPNOTSUPP;
+				goto unlock;
 			}
 			obuf[0] = msg[i].len;
 			obuf[1] = msg[i+1].len;
···
 			if (2 + msg[i].len > sizeof(obuf)) {
 				warn("i2c wr: len=%d is too big!\n",
 				     msg[i].len);
-				return -EOPNOTSUPP;
+				ret = -EOPNOTSUPP;
+				goto unlock;
 			}
 			obuf[0] = msg[i].addr;
 			obuf[1] = msg[i].len;
···
 		}
 	}
 
+	if (i == num)
+		ret = num;
+	else
+		ret = -EREMOTEIO;
+
+unlock:
 	mutex_unlock(&d->i2c_mutex);
-	return i == num ? num : -EREMOTEIO;
+	return ret;
 }
 
 static u32 cxusb_i2c_func(struct i2c_adapter *adapter)