ARM: dts: ls1021a: change dma channels order to match schema

Although the ordering of DMA channels was not relevant in the txt binding,
it is defined as ordered in the converted yaml schema.  Update the dts
to match the order.

Signed-off-by: Li Yang <leoyang.li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>