We have all of mach-omap2 booting in device tree only
mode now, and this data is populated from device tree.

Note that once we have removed support for the omap legacy
DMA, we can also drop struct omap_dma_dev_attr.

Cc: Lokesh Vutla <lokeshvutla@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: NTony Lindgren <tony@atomide.com>