ARM: dts: aspeed: Common dtsi for Facebook AST2400 Network BMCs

This common descirption is included by all Facebook AST2400 Network BMC
platforms to minimize duplicated device entries across Facebook Network
BMC device trees.

Signed-off-by: Tao Ren <rentao.bupt@gmail.com>
Reviewed-by: Patrick Williams <patrick@stwcx.xyz>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20201111232330.30843-2-rentao.bupt@gmail.com


Signed-off-by: Joel Stanley <joel@jms.id.au>