ASoC: speaer_pcm: No need to use snd_dmaengine_pcm_set_data()

The driver never uses snd_dmaengine_pcm_get_data(), so there is no need to use
snd_dmaengine_pcm_set_data().

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Rajeev Kumar <rajeev-dlh.kumar@st.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>