This patch introduce DMA device library internal header, which contains
internal data types that are used by the DMA devices in order to expose
their ops to the class.

Signed-off-by: Chengwen Feng <redacted>
Acked-by: Bruce Richardson <redacted>
Acked-by: Morten Brørup <redacted>
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<snip>

Reviewed-by: Conor Walsh <redacted>