tty: n_tty: rename and retype 'retval' in n_tty_ioctl()

The value stored to the current 'retval' is number of characters. It is
both obtained and put to user as unsigned. So make its type unsigned.
And provided it's not a "return value" per se, rename it to 'num'.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Jiri Slaby (SUSE)

drivers/tty/n_tty.c

@@ -2498,19 +2498,19 @@ static int n_tty_ioctl(struct tty_struct *tty, unsigned int cmd,
 		       unsigned long arg)
 {
 	struct n_tty_data *ldata = tty->disc_data;
-	int retval;
+	unsigned int num;
 
 	switch (cmd) {
 	case TIOCOUTQ:
 		return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
 	case TIOCINQ:
 		down_write(&tty->termios_rwsem);
 		if (L_ICANON(tty) && !L_EXTPROC(tty))
-			retval = inq_canon(ldata);
+			num = inq_canon(ldata);
 		else
-			retval = read_cnt(ldata);
+			num = read_cnt(ldata);
 		up_write(&tty->termios_rwsem);
-		return put_user(retval, (unsigned int __user *) arg);
+		return put_user(num, (unsigned int __user *) arg);
 	default:
 		return n_tty_ioctl_helper(tty, cmd, arg);
 	}