ARM: dts: aspeed-g6: Add UDMA node

Add the device tree node for the UART DMA (UDMA) controller.

Signed-off-by: Chia-Wei Wang <chiawei_wang@aspeedtech.com>
Link: https://lore.kernel.org/r/20230320081133.23655-6-chiawei_wang@aspeedtech.com


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