The snd_soc_dai_ops structures are only stored in the ops field of a
snd_soc_dai_driver structure, so make the snd_soc_dai_ops structures
const as well.

Done with the help of Coccinelle.
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Vinod Koul <vkoul@kernel.org>