ARM: dts: aspeed: Add Inventec Lanyang BMC

The Inventec Lanyang is Power 9 platform with ast2500 BMC.

Signed-off-by: Brian Yang <yang.brianc.w@inventec.com>
Acked-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>