ARM: dts: aspeed: Add Nuvia DC-SCM BMC

Add initial version of device tree for Nuvia DC-SCM BMC which is
equipped with Aspeed AST2600 BMC SoC.

Signed-off-by: Graeme Gregory <quic_ggregory@quicinc.com>
Signed-off-by: Jae Hyun Yoo <quic_jaehyoo@quicinc.com>
Link: https://lore.kernel.org/r/20220325190247.468079-1-quic_jaehyoo@quicinc.com
Signed-off-by: Joel Stanley <joel@jms.id.au>