powerpc/85xx: fix compatible properties of the P1022DS DMA nodes used for audio

In order to prevent the fsl_dma driver from claiming the DMA channels that the
P1022DS audio driver needs, the compatible properties for those nodes must say
"fsl,ssi-dma-channel" instead of "fsl,eloplus-dma-channel".

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>