tty: serial: samsung_tty: use console_is_registered()

It is not reliable to check for CON_ENABLED in order to identify if a
console is registered. Use console_is_registered() instead.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-29-john.ogness@linutronix.de

drivers/tty/serial/samsung_tty.c

@@ -1732,7 +1732,7 @@ static void __init s3c24xx_serial_register_console(void)
 
 static void s3c24xx_serial_unregister_console(void)
 {
-	if (s3c24xx_serial_console.flags & CON_ENABLED)
+	if (console_is_registered(&s3c24xx_serial_console))
 		unregister_console(&s3c24xx_serial_console);
 }