dmaengine: fix typos in comments

Spelling mistakes (triple letters) in comments.
Detected with the help of Coccinelle.

Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>

Link: https://lore.kernel.org/r/20220521111145.81697-51-Julia.Lawall@inria.fr


Signed-off-by: Vinod Koul <vkoul@kernel.org>