ARM: dts: aspeed: Add Qualcomm Centriq 2400 REP BMC

The Qualcomm Centriq 2400 REP (Reference Evaluation Platform) is
an aarch64 Armv8 server platform with an ast2520 BMC.

Signed-off-by: Ken Chen <chen.kenyy@inventec.com>
Acked-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>