tty: serial: samsung_tty: fix build warning

Fix a build warning on systems that do not have CONFIG_OF enabled.

Cc: Kukjin Kim <kgene@kernel.org>
Cc: Hyunki Koo <kkoos00@naver.com>
Cc: HYUN-KI KOO <hyunki00.koo@samsung.com>
Cc: Shinbeom Choi <sbeom.choi@samsung.com>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20191210143706.3928480-2-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/samsung_tty.c

@@ -1851,7 +1851,10 @@ static int s3c24xx_serial_init_port(struct s3c24xx_uart_port *ourport,
 
 /* Device driver serial port probe */
 
+#ifdef CONFIG_OF
 static const struct of_device_id s3c24xx_uart_dt_match[];
+#endif
+
 static int probe_index;
 
 static inline struct s3c24xx_serial_drv_data *s3c24xx_get_driver_data(