The dma pointer must be set to the passed stream pointer, even
if that pointer is NULL.

Fixes: e4961125 ("ASoC: cs35l56: Add driver for Cirrus Logic CS35L56")
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20230601124907.3128170-1-rf@opensource.cirrus.comSigned-off-by: Mark Brown <broonie@kernel.org>