hw/arm/aspeed: Add board model for Supermicro X11 BMC

hw/arm/aspeed: Add board model for Supermicro X11 BMC

The BMC Firmware can be downloaded from :

  https://www.supermicro.com/en/products/motherboard/X11SSL-F

Signed-off-by: Erik Smit <erik.lucas.smit@gmail.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
[ clg: Prettified Erik's name in email
       Modified commit log ]
Message-Id: <20200715173418.186-1-erik.lucas.smit@gmail.com>
Message-Id: <20200819100956.2216690-6-clg@kaod.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>