arm64: dts: freescale: ls1028a: Reorder sai dma-names to fix warning

Reorder the SAI dma-names to ensure "rx" precedes "tx" as required to fixes
the DTB_CHECK warning.

arch/arm64/boot/dts/freescale/fsl-ls1028a-rdb.dtb: audio-controller@f100000: dma-names:1: 'tx' was expected
	from schema $id: http://devicetree.org/schemas/sound/fsl,sai.yaml#


arm64/boot/dts/freescale/fsl-ls1028a-rdb.dtb: audio-controller@f110000: dma-names:1: 'tx' was expected

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