tty: sunsu: Simplify device_node cleanup by using __free

Add `__free` function attribute to `ap` and `match` pointer
initialisations which ensure that the pointers are freed as soon as they
go out of scope, thus removing the need to manually free them using
`of_node_put`.

This also removes the need for the `goto` statement and the `rc`
variable.

Suggested-by: Julia Lawall <julia.lawall@inria.fr>
Signed-off-by: Shresth Prasad <shresthprasad7@gmail.com>
Link: https://lore.kernel.org/r/20240518114051.18125-3-shresthprasad7@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Yttrium-32

drivers/tty/serial/sunsu.c

@@ -1382,44 +1382,29 @@ static inline struct console *SUNSU_CONSOLE(void)
 
 static enum su_type su_get_type(struct device_node *dp)
 {
-	struct device_node *ap = of_find_node_by_path("/aliases");
-	enum su_type rc = SU_PORT_PORT;
+	struct device_node *ap __free(device_node) =
+			    of_find_node_by_path("/aliases");
 
 	if (ap) {
 		const char *keyb = of_get_property(ap, "keyboard", NULL);
 		const char *ms = of_get_property(ap, "mouse", NULL);
-		struct device_node *match;
 
 		if (keyb) {
-			match = of_find_node_by_path(keyb);
+			struct device_node *match __free(device_node) =
+					    of_find_node_by_path(keyb);
 
-			/*
-			 * The pointer is used as an identifier not
-			 * as a pointer, we can drop the refcount on
-			 * the of__node immediately after getting it.
-			 */
-			of_node_put(match);
-
-			if (dp == match) {
-				rc = SU_PORT_KBD;
-				goto out;
-			}
+			if (dp == match)
+				return SU_PORT_KBD;
 		}
 		if (ms) {
-			match = of_find_node_by_path(ms);
+			struct device_node *match __free(device_node) =
+					    of_find_node_by_path(ms);
 
-			of_node_put(match);
-
-			if (dp == match) {
-				rc = SU_PORT_MS;
-				goto out;
-			}
+			if (dp == match)
+				return SU_PORT_MS;
 		}
 	}
-
-out:
-	of_node_put(ap);
-	return rc;
+	return SU_PORT_PORT;
 }
 
 static int su_probe(struct platform_device *op)