ARM: dts: aspeed: add device tree for YADRO VEGMAN BMC

YADRO VEGMAN is x86 based servers family with ASPEED AST2500-based BMC.
Currently there are three models:
* VEGMAN N110
* VEGMAN S220/320
* VEGMAN R120/220

The dts files provides configuration for BMC system.

Signed-off-by: Andrei Kartashev <a.kartashev@yadro.com>
Link: https://lore.kernel.org/r/20211119120057.12118-3-a.kartashev@yadro.com


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