serial: 8250_uniphier: fix dl_read and dl_write functions

The register offset must be shifted by regshift, otherwise the
baudrate is not set.  I missed the issue probably because the
divisor register was already set by the boot loader.

Fixes: 1a8d2903cb6a ("serial: 8250_uniphier: add UniPhier serial driver")
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_uniphier.c

@@ -115,12 +115,16 @@ static void uniphier_serial_out(struct uart_port *p, int offset, int value)
  */
 static int uniphier_serial_dl_read(struct uart_8250_port *up)
 {
-	return readl(up->port.membase + UNIPHIER_UART_DLR);
+	int offset = UNIPHIER_UART_DLR << up->port.regshift;
+
+	return readl(up->port.membase + offset);
 }
 
 static void uniphier_serial_dl_write(struct uart_8250_port *up, int value)
 {
-	writel(value, up->port.membase + UNIPHIER_UART_DLR);
+	int offset = UNIPHIER_UART_DLR << up->port.regshift;
+
+	writel(value, up->port.membase + offset);
 }
 
 static int uniphier_of_serial_setup(struct device *dev, struct uart_port *port,