powerpc/p1022: Add probing for individual DMA channels

Like the MPC8610 HPCD, the P1022DS ASoC DMA driver probes on individual DMA
channel nodes, so the DMA controller nodes' compatible string must be
listed in p1022_ds_ids[] to work.

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