ARM: dts: mxs: remove old DMA binding data from client nodes

After mxs-dma driver adopts generic DMA device tree binding, channel
interrupt number is defined in DMA controller node, and channel ID is
listed in "dmas" property.  So the DMA channel interrupt number in
client nodes' "interrupts" property and fsl,<module>-dma-channel which
are used by old customized DMA binding can be removed now.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>