The UART is present on the chipset regardless there is a
character device connected to it. Map it unconditionally.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Acked-by: Artyom Tarasenko <atar4qemu@gmail.com>
Reviewed-by: KONRAD Frederic <frederic.konrad@adacore.com>
Message-Id: <20200608172144.20461-2-f4bug@amsat.org>