serial: sh-sci: Fix cast warning

Fix the following compile warning about cast to pointer from
integer of different size.

drivers/tty/serial/sh-sci.c:2021:19: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/sh-sci.c

@@ -2018,7 +2018,7 @@ static int sci_remap_port(struct uart_port *port)
 		 * need to do any remapping, just cast the cookie
 		 * directly.
 		 */
-		port->membase = (void __iomem *)port->mapbase;
+		port->membase = (void __iomem *)(uintptr_t)port->mapbase;
 	}
 
 	return 0;