tty: serial: samsung: remove variable 'ufstat' set but not used

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/tty/serial/samsung_tty.c: In function s3c24xx_serial_rx_chars_dma:
drivers/tty/serial/samsung_tty.c:549:24: warning: variable ufstat set but not used [-Wunused-but-set-variable]
Signed-off-by: Chen Wandun <chenwandun@huawei.com>
Link: https://lore.kernel.org/r/1574424258-138975-1-git-send-email-chenwandun@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/samsung_tty.c

@@ -546,7 +546,7 @@ static void s3c24xx_serial_rx_drain_fifo(struct s3c24xx_uart_port *ourport);
 
 static irqreturn_t s3c24xx_serial_rx_chars_dma(void *dev_id)
 {
-	unsigned int utrstat, ufstat, received;
+	unsigned int utrstat, received;
 	struct s3c24xx_uart_port *ourport = dev_id;
 	struct uart_port *port = &ourport->port;
 	struct s3c24xx_uart_dma *dma = ourport->dma;
@@ -556,7 +556,7 @@ static irqreturn_t s3c24xx_serial_rx_chars_dma(void *dev_id)
 	struct dma_tx_state state;
 
 	utrstat = rd_regl(port, S3C2410_UTRSTAT);
-	ufstat = rd_regl(port, S3C2410_UFSTAT);
+	rd_regl(port, S3C2410_UFSTAT);
 
 	spin_lock_irqsave(&port->lock, flags);