USB: iowarrior: fix misuse of return value of copy_to_user()

copy_to_user() returns number of not copied bytes, not error code.
Signed-off-by: Kulikov Vasiliy <segooon@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/misc/iowarrior.c

@@ -542,7 +542,7 @@ static long iowarrior_ioctl(struct file *file, unsigned int cmd,
 			retval = io_res;
 		else {
 			io_res = copy_to_user(user_buffer, buffer, dev->report_size);
-			if (io_res < 0)
+			if (io_res)
 				retval = -EFAULT;
 		}
 		break;
@@ -574,7 +574,7 @@ static long iowarrior_ioctl(struct file *file, unsigned int cmd,
 			}
 			io_res = copy_to_user((struct iowarrior_info __user *)arg, &info,
 					 sizeof(struct iowarrior_info));
-			if (io_res < 0)
+			if (io_res)
 				retval = -EFAULT;
 			break;
 		}