TTY: move tty_lookup_driver to switch-cases

The labels express more the nature of the decision tree. We returned
from each if with a driver. Now we do this at the end of the function
and the code flow is clear.

While at it, remove an obsolete comment (we already take the
reference).
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/tty/tty_io.c

@@ -1841,16 +1841,17 @@ static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
 {
 	struct tty_driver *driver;
 
+	switch (device) {
 #ifdef CONFIG_VT
-	if (device == MKDEV(TTY_MAJOR, 0)) {
+	case MKDEV(TTY_MAJOR, 0): {
 		extern struct tty_driver *console_driver;
 		driver = tty_driver_kref_get(console_driver);
 		*index = fg_console;
 		*noctty = 1;
-		return driver;
+		break;
 	}
 #endif
-	if (device == MKDEV(TTYAUX_MAJOR, 1)) {
+	case MKDEV(TTYAUX_MAJOR, 1): {
 		struct tty_driver *console_driver = console_device(index);
 		if (console_driver) {
 			driver = tty_driver_kref_get(console_driver);
@@ -1858,15 +1859,17 @@ static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
 				/* Don't let /dev/console block */
 				filp->f_flags |= O_NONBLOCK;
 				*noctty = 1;
-				return driver;
+				break;
 			}
 		}
 		return ERR_PTR(-ENODEV);
 	}
-
-	driver = get_tty_driver(device, index);
-	if (!driver)
-		return ERR_PTR(-ENODEV);
+	default:
+		driver = get_tty_driver(device, index);
+		if (!driver)
+			return ERR_PTR(-ENODEV);
+		break;
+	}
 	return driver;
 }